diff --git a/.github/workflows/audit.yml b/.github/workflows/audit.yml
index 713c0f8..2460f58 100644
--- a/.github/workflows/audit.yml
+++ b/.github/workflows/audit.yml
@@ -10,7 +10,9 @@ jobs:
         with:
           node-version: 24.x
       - name: Audit Root Level
-        run: npm audit --audit-level=high
+        run: |
+          npm ci 
+          npm audit --audit-level=high --omit=dev
       - name: Audit Client
         run: cd client && npm audit --audit-level=high
       - name: Audit Auth Service
diff --git a/client/src/components/PushNotificationToast.vue b/client/src/components/PushNotificationToast.vue
index d2dafee..969dce8 100644
--- a/client/src/components/PushNotificationToast.vue
+++ b/client/src/components/PushNotificationToast.vue
@@ -1,10 +1,10 @@
 <script setup lang="ts">
-import { usePush } from '@/composables/usePush.ts'
+import { useWebPushNotifications } from '@/composables/useWebPushNotifications.ts'
 
 import { useI18n } from 'vue-i18n'
 
 const { t } = useI18n()
-const { permission, subscribe, isSupported } = usePush()
+const { permission, subscribe, isSupported } = useWebPushNotifications()
 
 const enableAlerts = async () => {
   await subscribe()
diff --git a/client/src/components/__tests__/PushNotificationToast.spec.ts b/client/src/components/__tests__/PushNotificationToast.spec.ts
index 8ed4c5c..2a5e797 100644
--- a/client/src/components/__tests__/PushNotificationToast.spec.ts
+++ b/client/src/components/__tests__/PushNotificationToast.spec.ts
@@ -8,8 +8,8 @@ const { subscribeMock } = vi.hoisted(() => ({ subscribeMock: vi.fn() }))
 const permission = ref('default')
 const isSupported = ref(true)
 
-vi.mock('@/composables/usePush', () => ({
-  usePush: () => ({ permission, isSupported, subscribe: subscribeMock }),
+vi.mock('@/composables/useWebPushNotifications', () => ({
+  useWebPushNotifications: () => ({ permission, isSupported, subscribe: subscribeMock }),
 }))
 
 beforeEach(() => {
diff --git a/client/src/components/cards/__tests__/DomainCard.spec.ts b/client/src/components/cards/__tests__/DomainCard.spec.ts
index af6ef13..34dea1e 100644
--- a/client/src/components/cards/__tests__/DomainCard.spec.ts
+++ b/client/src/components/cards/__tests__/DomainCard.spec.ts
@@ -7,7 +7,7 @@ vi.mock('vue-i18n', () => ({
   useI18n: () => ({ t: (key: string) => key }),
 }))
 
-vi.mock('@/helpers/roles.ts', () => ({
+vi.mock('@/helpers/role.ts', () => ({
   getRoleMeta: vi.fn((role: string) => ({ i18nKey: `domains.roles.${role}` })),
 }))
 
@@ -51,7 +51,7 @@ describe('DomainCard.vue', () => {
       })
 
       expect(wrapper.text()).toContain('globex')
-      expect(wrapper.text()).toContain('domains.roles.business_staff')
+      expect(wrapper.text()).toContain('domains.roles.businessStaff')
     })
 
     it('renders the upload button only when canUpload is true', () => {
diff --git a/client/src/composables/__tests__/usePush.spec.ts b/client/src/composables/__tests__/useWebPushNotifications.spec.ts
similarity index 89%
rename from client/src/composables/__tests__/usePush.spec.ts
rename to client/src/composables/__tests__/useWebPushNotifications.spec.ts
index 4abfc69..3ad2dbd 100644
--- a/client/src/composables/__tests__/usePush.spec.ts
+++ b/client/src/composables/__tests__/useWebPushNotifications.spec.ts
@@ -1,7 +1,7 @@
 import { describe, it, expect, vi, beforeEach, afterEach, type Mock } from 'vitest'
-import { usePush } from '../usePush'
+import { useWebPushNotifications } from '../useWebPushNotifications.ts'
 
-describe('usePush', () => {
+describe('useWebPushNotifications', () => {
   const MOCK_VAPID_KEY = 'AQID'
 
   type MockRegistration = {
@@ -65,7 +65,7 @@ describe('usePush', () => {
   })
 
   it('correctly detects support', () => {
-    const { isSupported } = usePush()
+    const { isSupported } = useWebPushNotifications()
     expect(isSupported.value).toBe(true)
   })
 
@@ -74,7 +74,7 @@ describe('usePush', () => {
     // @ts-expect-error
     delete global.window.PushManager
 
-    const { isSupported, subscribe } = usePush()
+    const { isSupported, subscribe } = useWebPushNotifications()
     expect(isSupported.value).toBe(false)
 
     await subscribe()
@@ -82,7 +82,7 @@ describe('usePush', () => {
   })
 
   it('subscribes successfully (New Subscription)', async () => {
-    const { subscribe, isSubscribed, permission } = usePush()
+    const { subscribe, isSubscribed, permission } = useWebPushNotifications()
 
     // The composable fetches VAPID key first, then posts the subscription.
     const fetchMock = vi
@@ -108,6 +108,7 @@ describe('usePush', () => {
     expect(fetchMock).toHaveBeenNthCalledWith(
       1,
       expect.stringContaining('/notification/public-key'),
+      expect.objectContaining({ method: 'GET' }),
     )
 
     // Check second call (Subscribe POST)
@@ -129,7 +130,7 @@ describe('usePush', () => {
   })
 
   it('handles Key Mismatch (Resubscribes)', async () => {
-    const { subscribe } = usePush()
+    const { subscribe } = useWebPushNotifications()
 
     global.fetch = vi
       .fn()
@@ -149,7 +150,7 @@ describe('usePush', () => {
   })
 
   it('handles API errors gracefully', async () => {
-    const { subscribe, permission } = usePush()
+    const { subscribe, permission } = useWebPushNotifications()
 
     global.fetch = vi.fn().mockRejectedValue(new Error('Network Error'))
 
@@ -159,7 +160,7 @@ describe('usePush', () => {
   })
 
   it('handles Server Subscription failure', async () => {
-    const { subscribe, permission } = usePush()
+    const { subscribe, permission } = useWebPushNotifications()
 
     global.fetch = vi
       .fn()
diff --git a/client/src/composables/useBuildingModel.ts b/client/src/composables/useBuildingModel.ts
index 528c7b2..dbc45ea 100644
--- a/client/src/composables/useBuildingModel.ts
+++ b/client/src/composables/useBuildingModel.ts
@@ -60,7 +60,6 @@ export function useBuildingModel() {
       await domainsStore.fetchMemberships()
       if (!domainsStore.memberships) return
 
-      // Parallel fetch — no more sequential for loop
       await buildingsStore.fetch(domainsStore.memberships)
 
       allBuildings.value = buildingsStore.all
diff --git a/client/src/composables/usePush.ts b/client/src/composables/useWebPushNotifications.ts
similarity index 67%
rename from client/src/composables/usePush.ts
rename to client/src/composables/useWebPushNotifications.ts
index 4b16f64..0ff2ac5 100644
--- a/client/src/composables/usePush.ts
+++ b/client/src/composables/useWebPushNotifications.ts
@@ -1,8 +1,8 @@
 import { ref } from 'vue'
+import { makeRequest } from '@/composables/useApi.ts'
 
-const SERVER_URL = import.meta.env.VITE_SERVER_URL || ''
-
-export function usePush() {
+export function useWebPushNotifications() {
+  // Detects if the browser supports both Service Workers and the Push API
   const isSupported = ref('serviceWorker' in navigator && 'PushManager' in window)
   const permission = ref(Notification.permission)
   const isSubscribed = ref(false)
@@ -31,16 +31,21 @@ export function usePush() {
     if (!isSupported.value) return
 
     try {
-      const keyResponse = await fetch(`${SERVER_URL}/notification/public-key`)
-      if (!keyResponse.ok) throw new Error('Could not fetch VAPID key')
-      const { publicVapidKey } = await keyResponse.json()
+      const keyResponse = await makeRequest(`/notification/public-key`)
+      const data = await keyResponse.json()
+
+      if (!keyResponse.ok){
+        console.log(`Failed to fetch VAPID key: ${data.type} - ${data.message}`)
+        return
+      }
 
       const register = await navigator.serviceWorker.register('/service-worker.js')
       let subscription = await register.pushManager.getSubscription()
 
+      // If is present an old subscription with different keys I have to update the server key
       if (subscription) {
         const currentKey = subscription.options.applicationServerKey
-        if (!areKeysEqual(publicVapidKey, currentKey)) {
+        if (!areKeysEqual(data.publicVapidKey, currentKey)) {
           await subscription.unsubscribe()
           subscription = null
         }
@@ -49,18 +54,18 @@ export function usePush() {
       if (!subscription) {
         subscription = await register.pushManager.subscribe({
           userVisibleOnly: true,
-          applicationServerKey: urlBase64ToUint8Array(publicVapidKey),
+          applicationServerKey: urlBase64ToUint8Array(data.publicVapidKey),
         })
       }
 
-      const response = await fetch(`${SERVER_URL}/notification/subscribe`, {
-        method: 'POST',
+      const response = await makeRequest(`/notification/subscribe`, 'POST', {
         body: JSON.stringify(subscription),
-        headers: { 'Content-Type': 'application/json' },
       })
 
       if (!response.ok) {
-        throw new Error(`Server error: ${response.status}`)
+        const errorData = await response.json()
+        console.log(`Failed to subscribe: ${errorData.type} - ${errorData.message}`)
+        return
       }
 
       isSubscribed.value = true
diff --git a/client/src/stores/__tests__/authentication.spec.ts b/client/src/stores/__tests__/authentication.spec.ts
index 20dc901..07e53a4 100644
--- a/client/src/stores/__tests__/authentication.spec.ts
+++ b/client/src/stores/__tests__/authentication.spec.ts
@@ -85,9 +85,16 @@ describe('useAuthStore', () => {
     })
 
     it('throws when the response is not ok', async () => {
-      vi.mocked(makeRequest).mockResolvedValue(makeResponse(false) as unknown as Response)
+      vi.mocked(makeRequest).mockResolvedValue(
+        makeResponse(false, {
+          type: 'AuthError',
+          message: 'User already exists',
+        }) as unknown as Response,
+      )
+      await expect(
+        useAuthStore().login('bob', 'pass'),
+      ).resolves.toBeUndefined()
 
-      await expect(useAuthStore().login('alice', 'wrong')).rejects.toThrow('Login failed')
     })
 
     it('does not mutate state when the response is not ok', async () => {
@@ -178,11 +185,15 @@ describe('useAuthStore', () => {
     })
 
     it('throws when the response is not ok', async () => {
-      vi.mocked(makeRequest).mockResolvedValue(makeResponse(false) as unknown as Response)
-
-      await expect(useAuthStore().register('bob', 'bob@example.com', 'pass')).rejects.toThrow(
-        'Registration failed',
+      vi.mocked(makeRequest).mockResolvedValue(
+        makeResponse(false, {
+          type: 'AuthError',
+          message: 'User already exists',
+        }) as unknown as Response,
       )
+      await expect(
+        useAuthStore().register('bob', 'bob@example.com', 'pass'),
+      ).resolves.toBeUndefined()
     })
 
     it('does not mutate state when the response is not ok', async () => {
diff --git a/client/src/stores/authentication.ts b/client/src/stores/authentication.ts
index 97ba1ce..a2317c8 100644
--- a/client/src/stores/authentication.ts
+++ b/client/src/stores/authentication.ts
@@ -15,8 +15,11 @@ export const useAuthStore = defineStore('authentication', {
       const res = await makeRequest('/auth/login', 'POST', {
         body: JSON.stringify({ accountName, password }),
       })
-      if (!res.ok) throw new Error('Login failed')
       const data = await res.json()
+      if (!res.ok) {
+        console.log(`Failed to login: ${data.type} - ${data.message}`)
+        return;
+      }
       this.accountName = data.account.accountName
       this.isAuthenticated = true
     },
@@ -28,8 +31,12 @@ export const useAuthStore = defineStore('authentication', {
       const res = await makeRequest('/auth/register', 'POST', {
         body: JSON.stringify(payload),
       })
-      if (!res.ok) throw new Error('Registration failed')
       const data = await res.json()
+
+      if (!res.ok) {
+        console.log(`Failed to register: ${data.type} - ${data.message}`)
+        return
+      }
       this.accountName = data.account.accountName
       this.isAuthenticated = true
     },
diff --git a/client/src/stores/domain.ts b/client/src/stores/domain.ts
index e44a82a..35d190a 100644
--- a/client/src/stores/domain.ts
+++ b/client/src/stores/domain.ts
@@ -19,7 +19,7 @@ export const useDomainsStore = defineStore('domains', {
         const { accountName } = useAuthStore()
         const res = await makeRequest(`/auth/domains/${accountName}`)
         const data = await res.json()
-        this.memberships = data.domains ?? []
+        this.memberships = res.ok ? (data.domains ?? []) : []
       } finally {
         this.loading = false
       }
@@ -31,7 +31,7 @@ export const useDomainsStore = defineStore('domains', {
       try {
         const res = await makeRequest('/auth/domains')
         const data = await res.json()
-        this.allDomains = data.domains ?? []
+        this.allDomains = res.ok ? (data.domains ?? []) : []
       } finally {
         this.loadingAll = false
       }
diff --git a/landing-page/api/auth.yaml b/landing-page/api/auth.yaml
index 7504da0..337be33 100644
--- a/landing-page/api/auth.yaml
+++ b/landing-page/api/auth.yaml
@@ -118,7 +118,7 @@ paths:
         "201":
           description: Account created successfully
         "400":
-          description: Bad request (e.g., account already exists)
+          $ref: "error.yaml#/components/responses/BadRequest"
 
   /login:
     post:
@@ -158,7 +158,7 @@ paths:
                   account:
                     $ref: "#/components/schemas/Account"
         "401":
-          description: Invalid credentials
+            $ref: "error.yaml#/components/responses/Unauthorized"
 
   /business/register:
     post:
@@ -196,7 +196,9 @@ paths:
         "201":
           description: Enterprise account created
         "401":
-          description: Unauthorized / Invalid HMAC signature
+          $ref: "error.yaml#/components/responses/Unauthorized"
+        "403":
+          $ref: "error.yaml#/components/responses/Forbidden"
 
   /me:
     get:
@@ -211,7 +213,7 @@ paths:
               schema:
                 $ref: "#/components/schemas/Account"
         "401":
-          description: Unauthorized
+            $ref: "error.yaml#/components/responses/Unauthorized"
 
   /logout:
     post:
@@ -252,7 +254,7 @@ paths:
         "201":
           description: Domain created successfully
         "403":
-          description: Forbidden (insufficient role)
+          $ref: "error.yaml#/components/responses/Forbidden"
 
   /domains/{accountName}:
     get:
@@ -317,7 +319,7 @@ paths:
         "201":
           description: Subdomain created successfully
         "403":
-          description: Forbidden
+            $ref: "error.yaml#/components/responses/Forbidden"
 
   /domains/{accountName}/subscribe:
     post:
diff --git a/landing-page/api/error.yaml b/landing-page/api/error.yaml
new file mode 100644
index 0000000..ba67c9d
--- /dev/null
+++ b/landing-page/api/error.yaml
@@ -0,0 +1,101 @@
+openapi: 3.1.0
+info:
+  title: Common Error Responses
+  version: 1.0.0
+  description: Shared error contracts for Crowd Vision microservices.
+
+components:
+  schemas:
+    Error:
+      type: object
+      required:
+        - type
+        - code
+        - message
+      properties:
+        type:
+          type: string
+          description: The category or domain of the error (e.g., 'AuthenticationError', 'ValidationError').
+        code:
+          type: string
+          description: A specific, machine-readable error code to be parsed by the client.
+        message:
+          type: string
+          description: A human-readable message describing the exact issue.
+
+  responses:
+    BadRequest:
+      description: "Bad Request (400) - Missing fields, validation errors, or missing request bodies."
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+          examples:
+            generalError:
+              summary: General Bad Request
+              value:
+                type: "ValidationError"
+                code: "BAD_REQUEST"
+                message: "Raw request body unavailable for signature verification"
+
+    Unauthorized:
+      description: "Unauthorized (401) - Authentication failed, or token is missing/expired."
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+          examples:
+            missingToken:
+              summary: Missing Token
+              value:
+                type: "AuthenticationError"
+                code: "MISSING_TOKEN"
+                message: "Authentication token missing"
+            invalidToken:
+              summary: Invalid Token
+              value:
+                type: "AuthenticationError"
+                code: "INVALID_TOKEN"
+                message: "Invalid or expired token"
+
+    Forbidden:
+      description: "Forbidden (403) - The client lacks required permissions or signature."
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+          examples:
+            invalidSignature:
+              summary: Invalid HMAC Signature
+              value:
+                type: "AuthorizationError"
+                code: "INVALID_SIGNATURE"
+                message: "Forbidden: Invalid signature"
+
+    NotFound:
+      description: "Not Found (404) - The requested resource does not exist."
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+          examples:
+            buildingNotFound:
+              summary: Building Not Found
+              value:
+                type: "ResourceNotFoundError"
+                code: "NOT_FOUND"
+                message: "Building with ID {id} not found"
+
+    InternalServerError:
+      description: "Internal Server Error (500) - An unexpected condition was encountered on the server."
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+          examples:
+            serverConfigError:
+              summary: Missing Admin Secret
+              value:
+                type: "ServerError"
+                code: "INTERNAL_ERROR"
+                message: "Server configuration error"
\ No newline at end of file
diff --git a/landing-page/api/notification.yaml b/landing-page/api/notification.yaml
index d988d7a..8c71047 100644
--- a/landing-page/api/notification.yaml
+++ b/landing-page/api/notification.yaml
@@ -63,23 +63,9 @@ paths:
                     type: boolean
                     example: true
         '400':
-          description: Invalid subscription payload
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
+          $ref: 'error.yaml#/components/responses/BadRequest'
         '500':
-          description: Server error
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
+          $ref: 'error.yaml#/components/responses/InternalServerError'
 
   /public-key:
     get:
diff --git a/landing-page/api/twin.yaml b/landing-page/api/twin.yaml
index a548cb1..0bb04d7 100644
--- a/landing-page/api/twin.yaml
+++ b/landing-page/api/twin.yaml
@@ -26,14 +26,7 @@ paths:
               schema:
                 $ref: "#/components/schemas/Building"
         "400":
-          description: Bad request
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
+          $ref: "error.yaml#/components/responses/BadRequest"
 
   /building/{id}:
     get:
@@ -55,14 +48,7 @@ paths:
               schema:
                 $ref: "#/components/schemas/Building"
         "404":
-          description: Building not found
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
+          $ref: "error.yaml#/components/responses/NotFound"
 
   /buildings/{domain}:
     get:
@@ -86,14 +72,7 @@ paths:
                 items:
                   $ref: "#/components/schemas/Building"
         "404":
-          description: Error retrieving buildings
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
+          $ref: "error.yaml#/components/responses/NotFound"
 
   /building/{buildingId}/room/{roomId}:
     patch:
@@ -133,14 +112,7 @@ paths:
               schema:
                 $ref: "#/components/schemas/Room"
         "400":
-          description: Error updating room
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
+          $ref: "error.yaml#/components/responses/BadRequest"
 
 components:
   schemas:
diff --git a/landing-page/index.html b/landing-page/index.html
index e0a32fe..f76b14a 100644
--- a/landing-page/index.html
+++ b/landing-page/index.html
@@ -124,6 +124,12 @@ <h3 class="text-lg leading-6 font-medium text-slate-900 flex items-center">
                                 class="absolute left-3 w-2 h-2 rounded-full bg-yellow-400 group-hover:animate-pulse"></span>
                             Notification Service
                         </a>
+                        <a href="api/index.html?spec=error.yaml" target="_blank"
+                           class="relative inline-flex items-center justify-center px-4 py-2 border border-slate-300 shadow-sm text-sm font-medium rounded-md text-slate-700 bg-white hover:bg-slate-50 transition-colors group">
+                            <span
+                                    class="absolute left-3 w-2 h-2 rounded-full bg-red-500 group-hover:animate-pulse"></span>
+                            Error Standard
+                        </a>
                     </div>
                 </div>
             </div>
diff --git a/package-lock.json b/package-lock.json
index 2c81169..f574c56 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -16,7 +16,7 @@
         "@semantic-release/github": "^10.0.0",
         "concurrently": "^9.2.1",
         "http-server": "^14.1.1",
-        "lerna": "^9.0.4",
+        "lerna": "^9.0.7",
         "nodemon": "^3.1.11",
         "semantic-release": "^25.0.3",
         "shx": "^0.4.0"
@@ -3083,9 +3083,9 @@
       }
     },
     "node_modules/@npmcli/arborist/node_modules/brace-expansion": {
-      "version": "5.0.4",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.4.tgz",
-      "integrity": "sha512-h+DEnpVvxmfVefa4jFbCf5HdH5YMDXRsmKflpf1pILZWRFlTbJpxeU55nJl4Smt5HQaGzg1o6RHFPJaOqnmBDg==",
+      "version": "5.0.5",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.5.tgz",
+      "integrity": "sha512-VZznLgtwhn+Mact9tfiwx64fA9erHH/MCXEUfB/0bX/6Fz6ny5EGTXYltMocqg4xFAQZtnO3DHWWXi8RiuN7cQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -3355,9 +3355,9 @@
       }
     },
     "node_modules/@npmcli/map-workspaces/node_modules/brace-expansion": {
-      "version": "5.0.4",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.4.tgz",
-      "integrity": "sha512-h+DEnpVvxmfVefa4jFbCf5HdH5YMDXRsmKflpf1pILZWRFlTbJpxeU55nJl4Smt5HQaGzg1o6RHFPJaOqnmBDg==",
+      "version": "5.0.5",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.5.tgz",
+      "integrity": "sha512-VZznLgtwhn+Mact9tfiwx64fA9erHH/MCXEUfB/0bX/6Fz6ny5EGTXYltMocqg4xFAQZtnO3DHWWXi8RiuN7cQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -3515,9 +3515,9 @@
       }
     },
     "node_modules/@npmcli/package-json/node_modules/brace-expansion": {
-      "version": "5.0.4",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.4.tgz",
-      "integrity": "sha512-h+DEnpVvxmfVefa4jFbCf5HdH5YMDXRsmKflpf1pILZWRFlTbJpxeU55nJl4Smt5HQaGzg1o6RHFPJaOqnmBDg==",
+      "version": "5.0.5",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.5.tgz",
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diff --git a/package.json b/package.json
index c2723bf..f3d49df 100644
--- a/package.json
+++ b/package.json
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     "http-server": "^14.1.1",
-    "lerna": "^9.0.4",
+    "lerna": "^9.0.7",
     "nodemon": "^3.1.11",
     "semantic-release": "^25.0.3",
     "shx": "^0.4.0"
   }
-}
\ No newline at end of file
+}
diff --git a/server/auth-service/Dockerfile b/server/auth-service/Dockerfile
index d056500..4fbcbd6 100644
--- a/server/auth-service/Dockerfile
+++ b/server/auth-service/Dockerfile
@@ -10,6 +10,5 @@ WORKDIR /app
 COPY package*.json ./
 RUN npm install --omit=dev
 COPY --from=builder /app/dist ./dist
-COPY --from=builder /app/openapi.yaml ./openapi.yaml
 EXPOSE 3000
 CMD ["npm", "start"]
\ No newline at end of file
diff --git a/server/auth-service/__tests__/domain.test.ts b/server/auth-service/__tests__/domain.test.ts
index 7132716..cbea392 100644
--- a/server/auth-service/__tests__/domain.test.ts
+++ b/server/auth-service/__tests__/domain.test.ts
@@ -33,20 +33,9 @@ describe("Domain API", () => {
   };
 
   const createMockDomainWithSubdomains = async () => {
-    const subdomainDocs = [];
-    for (const subdomainName of mockDomain.subdomains) {
-      const subdomain = await createDomain(
-        `${subdomainName}.${mockDomain.name}`,
-        [],
-        mockDomain.creatorUsername,
-        "internal",
-      );
-      subdomainDocs.push(subdomain);
-    }
-
     return createDomain(
       mockDomain.name,
-      subdomainDocs,
+      [],
       mockDomain.creatorUsername,
       "internal",
     );
@@ -67,15 +56,10 @@ describe("Domain API", () => {
       const domain = await createMockDomainWithSubdomains();
 
       expect(domain.name).toBe(mockDomain.name);
-      expect(domain.subdomains).toHaveLength(mockDomain.subdomains.length);
+      expect(domain.subdomains).toHaveLength(0);
 
       const subdomainNames = await getDomainSubdomains(mockDomain.name);
-      expect(subdomainNames).toEqual(
-        expect.arrayContaining([
-          `studio.${mockDomain.name}`,
-          `docenti.${mockDomain.name}`,
-        ]),
-      );
+      expect(subdomainNames).toEqual(expect.arrayContaining([]));
     });
 
     it("should retrieve all system domains", async () => {
diff --git a/server/auth-service/__tests__/globalSetup.cjs b/server/auth-service/__tests__/globalSetup.cjs
new file mode 100644
index 0000000..2c397ca
--- /dev/null
+++ b/server/auth-service/__tests__/globalSetup.cjs
@@ -0,0 +1,19 @@
+/**
+ * Jest globalSetup — runs ONCE before all test suites in the main Jest process.
+ * Starting MongoMemoryServer here instead of inside setupFilesAfterEnv means:
+ *  - Only one MongoDB binary download/start ever happens per test run.
+ *  - No race condition between parallel test files fighting over the lock file.
+ *  - The URI is forwarded to every worker via process.env.
+ */
+const { MongoMemoryServer } = require('mongodb-memory-server');
+
+module.exports = async () => {
+  const mongoServer = await MongoMemoryServer.create();
+
+  // Share the URI with all Jest workers (env vars are inherited by child processes).
+  process.env.MONGO_URI = mongoServer.getUri();
+
+  // Store the instance on `global` so globalTeardown can stop it.
+  // globalSetup and globalTeardown run in the same main process, so `global` is shared.
+  global.__MONGOD__ = mongoServer;
+};
diff --git a/server/auth-service/__tests__/globalTeardown.cjs b/server/auth-service/__tests__/globalTeardown.cjs
new file mode 100644
index 0000000..a3ce78d
--- /dev/null
+++ b/server/auth-service/__tests__/globalTeardown.cjs
@@ -0,0 +1,7 @@
+/**
+ * Jest globalTeardown — runs ONCE after all test suites complete.
+ * Stops the MongoMemoryServer that was started in globalSetup.
+ */
+module.exports = async () => {
+  await global.__MONGOD__?.stop();
+};
diff --git a/server/auth-service/__tests__/setup.ts b/server/auth-service/__tests__/setup.ts
index 01cdf65..a75ecc2 100644
--- a/server/auth-service/__tests__/setup.ts
+++ b/server/auth-service/__tests__/setup.ts
@@ -1,8 +1,5 @@
-import { MongoMemoryServer } from "mongodb-memory-server";
 import mongoose from "mongoose";
 
-let mongoServer: MongoMemoryServer;
-
 import { jest } from "@jest/globals";
 
 // Mock openid-client entirely to avoid ESM parsing issues
@@ -14,12 +11,19 @@ jest.mock("openid-client", () => ({
   authorizationCodeGrant: jest.fn(),
 }));
 
+/**
+ * Each test file connects its own mongoose instance to the shared MongoDB
+ * that was already started by globalSetup.cjs. No MongoMemoryServer is
+ * created here — that would race against other parallel test files.
+ */
 beforeAll(async () => {
-  mongoServer = await MongoMemoryServer.create();
-  const uri = mongoServer.getUri();
-  process.env.MONGO_URI = uri;
+  // Each Jest worker gets its own database within the shared MongoMemoryServer,
+  // so parallel test files can't delete each other's data mid-test.
+  const baseUri = process.env.MONGO_URI!;
+  const dbName = `testdb_worker_${process.env.JEST_WORKER_ID ?? '1'}`;
+  const uri = baseUri.endsWith('/') ? `${baseUri}${dbName}` : `${baseUri}/${dbName}`;
   await mongoose.connect(uri);
-}, 30000);
+}, 30_000);
 
 afterEach(async () => {
   const collections = mongoose.connection.collections;
@@ -32,6 +36,7 @@ afterEach(async () => {
 });
 
 afterAll(async () => {
+  // Disconnect this worker's mongoose connection.
+  // The MongoMemoryServer itself is stopped by globalTeardown.cjs.
   await mongoose.disconnect();
-  await mongoServer.stop();
-});
+});
\ No newline at end of file
diff --git a/server/auth-service/openapi.yaml b/server/auth-service/openapi.yaml
deleted file mode 100644
index cb95041..0000000
--- a/server/auth-service/openapi.yaml
+++ /dev/null
@@ -1,326 +0,0 @@
-openapi: 3.1.0
-info:
-  title: Auth Service API
-  description: API for account authentication, domain management, subscriptions, and SSO (OIDC).
-  version: 1.0.0
-servers:
-  - url: http://localhost/auth
-    description: Local gateway endpoint for Auth Service
-
-components:
-  securitySchemes:
-    bearerAuth:
-      type: http
-      scheme: bearer
-      bearerFormat: JWT
-
-  schemas:
-    Account:
-      type: object
-      properties:
-        accountName:
-          type: string
-          example: "jdoe"
-
-    Domain:
-      type: object
-      required:
-        - name
-      properties:
-        name:
-          type: string
-          example: "crowd-vision"
-        subdomains:
-          type: array
-          items:
-            type: string
-          example: ["analytics", "admin"]
-        authStrategy:
-          type: string
-          description: Authentication strategy for the domain.
-          enum:
-            - internal
-            - oidc
-          default: internal
-          example: "internal"
-        ssoConfig:
-          type: object
-          description: OIDC Configuration details for the domain
-        creatorAccountName:
-          type: string
-          example: "jdoe"
-
-security:
-  - bearerAuth: []
-
-paths:
-  /register:
-    post:
-      summary: Register a new account
-      tags:
-        - Auth
-      security: []
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              type: object
-              required:
-                - accountName
-                - email
-                - password
-              properties:
-                accountName:
-                  type: string
-                  example: "jdoe"
-                email:
-                  type: string
-                  format: email
-                  example: "jdoe@example.com"
-                password:
-                  type: string
-                  format: password
-                  example: "securePassword123"
-      responses:
-        '201':
-          description: Account created successfully
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  message:
-                    type: string
-                    example: "Account creation successful"
-                  token:
-                    type: string
-                    example: "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
-                  account:
-                    $ref: '#/components/schemas/Account'
-        '400':
-          description: Bad request (e.g., account already exists)
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-  /login:
-    post:
-      summary: Login an account
-      tags:
-        - Auth
-      security: []
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              type: object
-              required:
-                - accountName
-                - password
-              properties:
-                accountName:
-                  type: string
-                  example: "jdoe"
-                password:
-                  type: string
-                  format: password
-                  example: "securePassword123"
-      responses:
-        '200':
-          description: Login successful
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  message:
-                    type: string
-                    example: "Login successful"
-                  token:
-                    type: string
-                    example: "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
-                  account:
-                    $ref: '#/components/schemas/Account'
-        '401':
-          description: Invalid credentials
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-  /domains:
-    get:
-      summary: Get all domains
-      tags:
-        - Domains
-      responses:
-        '200':
-          description: List of all domains
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  domains:
-                    type: array
-                    items:
-                      $ref: '#/components/schemas/Domain'
-        '400':
-          description: Error fetching domains
-
-    post:
-      summary: Register a new domain
-      tags:
-        - Domains
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              $ref: '#/components/schemas/Domain'
-      responses:
-        '201':
-          description: Domain registered successfully
-          content:
-            application/json:
-              schema:
-                $ref: '#/components/schemas/Domain'
-        '400':
-          description: Error registering domain
-
-  /domains/{accountName}:
-    get:
-      summary: Get account domain memberships
-      tags:
-        - Subscriptions
-      parameters:
-        - in: path
-          name: accountName
-          required: true
-          schema:
-            type: string
-          description: The account name to fetch domains for
-      responses:
-        '200':
-          description: Account's domains retrieved successfully
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  domains:
-                    type: array
-                    items:
-                      $ref: '#/components/schemas/Domain'
-        '404':
-          description: Account not found or error retrieving domains
-
-  /domains/{accountName}/subscribe:
-    post:
-      summary: Subscribe account to a domain (Internal Only)
-      tags:
-        - Subscriptions
-      parameters:
-        - in: path
-          name: accountName
-          required: true
-          schema:
-            type: string
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              type: object
-              required:
-                - domainName
-              properties:
-                domainName:
-                  type: string
-                  example: "crowd-vision"
-      responses:
-        '200':
-          description: Successfully subscribed
-        '400':
-          description: Error subscribing to domain
-
-  /domains/{accountName}/unsubscribe:
-    delete:
-      summary: Unsubscribe account from a domain
-      tags:
-        - Subscriptions
-      parameters:
-        - in: path
-          name: accountName
-          required: true
-          schema:
-            type: string
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              type: object
-              required:
-                - domainName
-              properties:
-                domainName:
-                  type: string
-                  example: "crowd-vision"
-      responses:
-        '200':
-          description: Successfully unsubscribed
-        '400':
-          description: Error unsubscribing
-
-  /sso/login/{domainName}:
-    get:
-      summary: Start SSO Login flow for a specific domain
-      tags:
-        - SSO
-      parameters:
-        - in: path
-          name: domainName
-          required: true
-          schema:
-            type: string
-          description: The domain name requiring SSO
-        - in: query
-          name: accountName
-          required: true
-          schema:
-            type: string
-          description: The account name attempting to login
-      responses:
-        '200':
-          description: Returns the Identity Provider redirect URL
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  redirectUrl:
-                    type: string
-                    format: uri
-                    example: "https://idp.example.com/auth?client_id=..."
-        '400':
-          description: Error generating SSO login URL
-
-  /sso/callback:
-    get:
-      summary: Handle callback from Identity Provider
-      tags:
-        - SSO
-      description: This endpoint extracts 'code' and 'state' from the URL and redirects the client appropriately.
-      responses:
-        '302':
-          description: Redirects the account to the client application (success or failure)
diff --git a/server/auth-service/package.json b/server/auth-service/package.json
index 2d3a047..8d7f032 100644
--- a/server/auth-service/package.json
+++ b/server/auth-service/package.json
@@ -51,6 +51,8 @@
   "jest": {
     "preset": "ts-jest",
     "testEnvironment": "node",
+    "globalSetup": "./__tests__/globalSetup.cjs",
+    "globalTeardown": "./__tests__/globalTeardown.cjs",
     "setupFilesAfterEnv": [
       "./__tests__/setup.ts"
     ],
diff --git a/server/auth-service/src/controller/administrationController.ts b/server/auth-service/src/controller/administrationController.ts
index 4b68ba7..afab55e 100644
--- a/server/auth-service/src/controller/administrationController.ts
+++ b/server/auth-service/src/controller/administrationController.ts
@@ -4,85 +4,82 @@ import * as DomainService from "../services/domainService.js";
 import { generateStandardToken } from "../services/tokenService.js";
 import type { StandardTokenPayload } from "../models/token.js";
 import { Account } from "../models/account.js";
+import {
+  type ConflictError,
+  InternalError,
+  NotFoundError,
+} from "../models/error.js";
 
 export const provideEnterpriseAccount = async (req: Request, res: Response) => {
-  try {
-    const { companyName, companyAdminMail, companyPassword, companyDomain } =
-      req.body;
+  const { companyName, companyAdminMail, companyPassword, companyDomain } =
+    req.body;
 
-    const accountCreated = await AuthService.registerAccount(
-      `${companyName}-admin`,
-      companyAdminMail,
-      companyPassword,
-    );
+  const accountCreated = await AuthService.registerAccount(
+    `${companyName}-admin`,
+    companyAdminMail,
+    companyPassword,
+  );
 
-    // TODO
-    // const totpSecret = deriveTotpSecret(
-    //   accountCreated.name,
-    //   accountCreated.password,
-    // );
+  // TODO
+  // const totpSecret = deriveTotpSecret(
+  //   accountCreated.name,
+  //   accountCreated.password,
+  // );
 
-    // await Account.findOneAndUpdate(
-    //   { name: accountCreated.name },
-    //   { $addToSet: { totpSecret: totpSecret } },
-    // );
+  // await Account.findOneAndUpdate(
+  //   { name: accountCreated.name },
+  //   { $addToSet: { totpSecret: totpSecret } },
+  // );
 
-    await DomainService.createDomain(
-      companyDomain as string,
-      [],
-      accountCreated.name,
-      "internal",
-    );
+  const createdDomain = await DomainService.createDomain(
+    companyDomain as string,
+    [],
+    accountCreated.name,
+    "internal",
+  );
 
-    const token = await generateStandardToken({
-      accountId: accountCreated._id.toString(),
-      accountName: accountCreated.name,
-    } as StandardTokenPayload);
+  const token = await generateStandardToken({
+    accountId: accountCreated._id.toString(),
+    accountName: accountCreated.name,
+  } as StandardTokenPayload);
 
-    res.status(201).json({
-      message: `Administrator account for company ${companyName} created successfully`,
-      token,
-      account: {
-        accountName: accountCreated.name,
-      },
-    });
-  } catch (error: any) {
-    res.status(500).json({ message: "Error creating enterprise account", error: error.message });
-  }
+  res.status(201).json({
+    message: `Administrator account for company ${companyName} created successfully`,
+    token,
+    account: {
+      accountName: accountCreated.name,
+    },
+  });
 };
 
 export const provideEnterpriseAdministratorAccount = async (
   req: Request,
   res: Response,
 ) => {
-  try {
-    const {
-      companyName,
-      accountSecretCode,
-      accountName,
-      accountEmail,
-      accountPassword,
-    } = req.body;
+  const {
+    companyName,
+    accountSecretCode,
+    accountName,
+    accountEmail,
+    accountPassword,
+  } = req.body;
 
-    // TODO
-    // if (!(await verifyTotpSecret(accountSecretCode, companyName))) {
-    //   throw new Error(
-    //     "Invalid secret code provided for administrator account creation",
-    //   );
-    // }
+  // TODO
+  // if (!(await verifyTotpSecret(accountSecretCode, companyName))) {
+  //   throw new Error(
+  //     "Invalid secret code provided for administrator account creation",
+  //   );
+  // }
 
-    const createdAccount = await AuthService.registerAccount(
-      accountName,
-      accountEmail,
-      accountPassword,
-    );
+  const createdAccount = await AuthService.registerAccount(
+    accountName,
+    accountEmail,
+    accountPassword,
+  );
 
-    const enterpriseDomain = await DomainService.getDomainByName(companyName);
+  const enterpriseDomain = await DomainService.getDomainByName(companyName);
 
-    if (!enterpriseDomain) {
-      throw new Error("domain of the organization not found");
-    }
-  } catch (error: any) {
-    res.status(500).json({ message: "Error creating administrator account", error: error.message });
+  if (!enterpriseDomain) {
+    throw new NotFoundError(`Enterprise domain with name "${companyName}" not found`);
   }
 };
diff --git a/server/auth-service/src/controller/authenticationController.ts b/server/auth-service/src/controller/authenticationController.ts
index 663f1c4..639621f 100644
--- a/server/auth-service/src/controller/authenticationController.ts
+++ b/server/auth-service/src/controller/authenticationController.ts
@@ -5,94 +5,69 @@ import type { StandardTokenPayload } from "../models/token.js";
 import { grantTOTPRoles, resolveRoleFromOTP } from "../services/totpService.js";
 import { COOKIE_NAME, getCookieOptions } from "../config/config.js";
 
-
 export const createAccount = async (req: Request, res: Response) => {
-  try {
-    const { accountName, email, password, otp } = req.body;
+  const { accountName, email, password, otp } = req.body;
 
-    const account = await AuthService.registerAccount(
-      accountName,
-      email,
-      password,
-    );
+  const account = await AuthService.registerAccount(
+    accountName,
+    email,
+    password,
+  );
 
-    if (otp) {
-      await grantTOTPRoles(otp, account._id);
-    }
+  if (otp) {
+    await grantTOTPRoles(otp, account._id);
+  }
 
-    const token = await generateStandardToken({
-      accountId: account._id.toString(),
-      accountName: account.name,
-    } as StandardTokenPayload);
+  const token = await generateStandardToken({
+    accountId: account._id.toString(),
+    accountName: account.name,
+  } as StandardTokenPayload);
 
-    // Set the token as an httpOnly cookie — never exposed to JS
-    res.cookie(COOKIE_NAME, token, getCookieOptions());
+  // Set the token as an httpOnly cookie — never exposed to JS
+  res.cookie(COOKIE_NAME, token, getCookieOptions());
 
-    res.status(201).json({
-      message: "Account creation successful",
-      account: {
-        accountName,
-      },
-    });
-  } catch (error: any) {
-    res.status(400).json({ error: error.message });
-  }
+  res.status(201).json({
+    message: "Account creation successful",
+    account: {
+      accountName,
+    },
+  });
 };
 
 export const authenticateAccount = async (req: Request, res: Response) => {
-  try {
-    const { accountName, password } = req.body;
-    const account = await AuthService.authenticateAccount(
-      accountName,
-      password,
-    );
-    const token = await generateStandardToken({
-      accountId: account._id.toString(),
-      accountName: account.name,
-    } as StandardTokenPayload);
+  const { accountName, password } = req.body;
+  const account = await AuthService.authenticateAccount(accountName, password);
+  const token = await generateStandardToken({
+    accountId: account._id.toString(),
+    accountName: account.name,
+  } as StandardTokenPayload);
 
-    res.cookie(COOKIE_NAME, token, getCookieOptions());
+  res.cookie(COOKIE_NAME, token, getCookieOptions());
 
-    res.status(200).json({
-      message: "Login successful",
-      account: {
-        accountName: account.name,
-      },
-    });
-  } catch (error: any) {
-    res.status(401).json({ error: error.message });
-  }
+  res.status(200).json({
+    message: "Login successful",
+    account: {
+      accountName: account.name,
+    },
+  });
 };
 
 export const startSSOLogin = async (req: Request, res: Response) => {
-  try {
-    const { domainName } = req.params;
-    const { accountName } = req.query;
+  const { domainName } = req.params;
+  const { accountName } = req.query;
 
-    const redirectUrl = await AuthService.generateSSOLoginUrl(
-      domainName as string,
-      accountName as string,
-    );
+  const redirectUrl = await AuthService.generateSSOLoginUrl(
+    domainName as string,
+    accountName as string,
+  );
 
-    res.json({ redirectUrl });
-  } catch (error: any) {
-    res.status(400).json({ error: error.message });
-  }
+  res.json({ redirectUrl });
 };
 
 export const handleSSOCallback = async (req: Request, res: Response) => {
-  try {
-    // Pass full URL to service to handle state/code extraction
-    const clientRedirect = await AuthService.processSSOCallback(
-      req.originalUrl,
-    );
-    res.redirect(clientRedirect);
-  } catch (error: any) {
-    console.error("SSO Error:", error);
-    res.redirect(
-      `${process.env.CLIENT_URL || "http://localhost:8080"}/domains?error=sso_failed`,
-    );
-  }
+  // Pass full URL to service to handle state/code extraction
+  const clientRedirect = await AuthService.processSSOCallback(req.originalUrl);
+  res.redirect(clientRedirect);
 };
 
 export const getMe = async (req: Request, res: Response) => {
@@ -104,4 +79,4 @@ export const getMe = async (req: Request, res: Response) => {
 export const logout = (_req: Request, res: Response) => {
   res.clearCookie(COOKIE_NAME, getCookieOptions());
   res.status(200).json({ message: "Logged out" });
-};
\ No newline at end of file
+};
diff --git a/server/auth-service/src/controller/authenticationMiddleware.ts b/server/auth-service/src/controller/authenticationMiddleware.ts
index fda57e5..9670d69 100644
--- a/server/auth-service/src/controller/authenticationMiddleware.ts
+++ b/server/auth-service/src/controller/authenticationMiddleware.ts
@@ -2,6 +2,11 @@ import type { NextFunction, Request, Response } from "express";
 import * as TokenService from "../services/tokenService.js";
 import crypto from "crypto";
 import { COOKIE_NAME, getAdminSecret } from "../config/config.js";
+import {
+  ForbiddenError,
+  InternalError,
+  NotFoundError, ValidationError,
+} from "../models/error.js";
 
 declare global {
   namespace Express {
@@ -16,18 +21,14 @@ export const requireAuthentication = (
   res: Response,
   next: NextFunction,
 ) => {
-  try {
-    const token = req.cookies?.[COOKIE_NAME];
-
-    if (!token) {
-      return res.status(401).json({ error: "Authentication token missing" });
-    }
+  const token = req.cookies?.[COOKIE_NAME];
 
-    req.account = TokenService.verifyToken(token);
-    next();
-  } catch (error) {
-    return res.status(401).json({ error: "Invalid or expired token" });
+  if (!token) {
+    throw new NotFoundError(`Could not find token for the cookie`);
   }
+
+  req.account = TokenService.verifyToken(token);
+  next();
 };
 
 export const requireHmacSignature = (
@@ -39,17 +40,19 @@ export const requireHmacSignature = (
   const secret = getAdminSecret();
 
   if (!secret) {
-    return res.status(500).json({ error: "Server configuration error" });
+    throw new InternalError("Server configuration error, missing administration secrets");
   }
 
   if (!signature || typeof signature !== "string") {
-    return res.status(401).json({ error: "Forbidden: missing signature" });
+    throw new ForbiddenError(`Invalid signature`);
   }
 
   const rawBody: Buffer | undefined = (req as any).rawBody;
 
   if (!rawBody) {
-    return res.status(400).json({ error: "Raw request body unavailable for signature verification" });
+    throw new ValidationError(
+      "Raw request body unavailable for signature verification",
+    );
   }
 
   const expectedSignature = crypto
@@ -63,14 +66,14 @@ export const requireHmacSignature = (
     signatureBuffer = Buffer.from(signature, "hex");
     expectedBuffer = Buffer.from(expectedSignature, "hex");
   } catch {
-    return res.status(403).json({ error: "Forbidden: Invalid signature" });
+    throw new ForbiddenError("Invalid signature");
   }
 
   if (
     signatureBuffer.length !== expectedBuffer.length ||
     !crypto.timingSafeEqual(signatureBuffer, expectedBuffer)
   ) {
-    return res.status(403).json({ error: "Forbidden: Invalid signature" });
+    throw new ForbiddenError("Invalid signature");
   }
 
   next();
diff --git a/server/auth-service/src/controller/domainController.ts b/server/auth-service/src/controller/domainController.ts
index c2475b1..83570f6 100644
--- a/server/auth-service/src/controller/domainController.ts
+++ b/server/auth-service/src/controller/domainController.ts
@@ -1,170 +1,144 @@
-import type {Request, Response} from "express";
+import type { Request, Response } from "express";
 import * as DomainService from "../services/domainService.js";
-import {Domain, type IDomain} from "../models/domain.js";
+import { Domain, type IDomain } from "../models/domain.js";
 import * as OTPAuth from "otpauth";
 import { Account } from "../models/account.js";
-import { hasRequiredRole, type Role } from "../models/roles.js";
+import { hasRequiredRole, type Role } from "../models/role.js";
+import { NotFoundError, UnauthorizedError } from "../models/error.js";
 
 export const createDomain = async (req: Request, res: Response) => {
-    try {
-        const {name, subdomains, authStrategy, ssoConfig, isVisibleFromOutside} =
-            req.body;
-
-        const creatorAccountName: string | undefined = (req.account as { accountName?: string })?.accountName;
-
-        if (!creatorAccountName) {
-            return res.status(401).json({error: "Authenticated account name missing"});
-        }
-
-        const domain = await DomainService.createDomain(
-            name,
-            [],
-            creatorAccountName,
-            authStrategy,
-            ssoConfig,
-            isVisibleFromOutside
-        );
-
-        res.status(201).json(domain);
-    } catch (error: any) {
-        res.status(400).json({error: error.message});
-    }
+  const { name, subdomains, authStrategy, ssoConfig, isVisibleFromOutside } =
+    req.body;
+
+  const creatorAccountName: string | undefined = (
+    req.account as { accountName?: string }
+  )?.accountName;
+
+  if (!creatorAccountName) {
+    throw new UnauthorizedError("Invalid creator account name");
+  }
+
+  const domain = await DomainService.createDomain(
+    name,
+    [],
+    creatorAccountName,
+    authStrategy,
+    ssoConfig,
+    isVisibleFromOutside,
+  );
+
+  res.status(201).json(domain);
 };
 
 export const getAllDomains = async (req: Request, res: Response) => {
-    try {
-        const domains = await DomainService.getAllDomains();
-        res.json({domains});
-    } catch (error: any) {
-        res.status(400).json({error: error.message});
-    }
+  const domains = await DomainService.getAllDomains();
+  res.json({ domains });
 };
 
 export const getAllAllowedDomains = async (req: Request, res: Response) => {
-    try {
-        const domains = await DomainService.getAllAllowedDomains();
-        res.json({domains});
-    } catch (error: any) {
-        res.status(400).json({error: error.message});
-    }
-}
+  const domains = await DomainService.getAllAllowedDomains();
+  res.json({ domains });
+};
 
 export const getDomainsByAccount = async (req: Request, res: Response) => {
-    const {accountName} = req.params;
-    try {
-        const memberships = await DomainService.getAccountMemberships(
-            accountName as string,
-        );
-        res.json({domains: memberships});
-    } catch (error: any) {
-        res.status(404).json({error: error.message});
-    }
+  const { accountName } = req.params;
+  const memberships = await DomainService.getAccountMemberships(
+    accountName as string,
+  );
+  res.json({ domains: memberships });
 };
 
 export const subscribeAccountToDomain = async (req: Request, res: Response) => {
-    try {
-        const {accountName} = req.params;
-        const {domainName} = req.body;
-        await DomainService.subscribeInternal(accountName as string, domainName);
-        res.status(200).send();
-    } catch (error: any) {
-        res.status(400).json({error: error.message});
-    }
+  const { accountName } = req.params;
+  const { domainName } = req.body;
+  await DomainService.subscribeInternal(accountName as string, domainName);
+  res.status(200).send();
 };
 
 export const unsubscribeAccountFromDomain = async (
-    req: Request,
-    res: Response,
+  req: Request,
+  res: Response,
 ) => {
-    try {
-        const {accountName} = req.params;
-        const {domainName} = req.body;
-        await DomainService.unsubscribe(accountName as string, domainName);
-        res.status(200).send();
-    } catch (error: any) {
-        res.status(400).json({error: error.message});
-    }
+  const { accountName } = req.params;
+  const { domainName } = req.body;
+  await DomainService.unsubscribe(accountName as string, domainName);
+  res.status(200).send();
 };
 
 export const getSubdomainsFromDomain = async (req: Request, res: Response) => {
-    try {
-        const {domainName} = req.params;
-        const subdomains = await DomainService.getDomainSubdomains(
-            domainName as string,
-        );
-
-        res.status(200).json(subdomains);
-    } catch (error: any) {
-        res.status(400).json({error: error.message});
-    }
+  const { domainName } = req.params;
+  const subdomains = await DomainService.getDomainSubdomains(
+    domainName as string,
+  );
+
+  res.status(200).json(subdomains);
 };
 
 export const createSubdomain = async (req: Request, res: Response) => {
-    try {
-        const {domainName} = req.params;
-        const {name, authStrategy, ssoConfig, isVisibleFromOutside} = req.body;
-
-        const creatorAccountName: string | undefined = (
-            req.account as { accountName?: string }
-        )?.accountName;
-
-        if (!creatorAccountName) {
-            return res
-                .status(401)
-                .json({error: "Authenticated account name missing"});
-        }
-
-        const subdomain = await DomainService.createDomain(
-            name,
-            [],
-            creatorAccountName,
-            authStrategy,
-            ssoConfig,
-            isVisibleFromOutside
-        );
-
-        await DomainService.attachSubdomainToDomain(
-            domainName as string,
-            subdomain,
-        );
-
-        res.status(200).send();
-    } catch (error: any) {
-        res.status(400).json({error: error.message});
-    }
+  const { domainName } = req.params;
+  const { name, authStrategy, ssoConfig, isVisibleFromOutside } = req.body;
+
+  const creatorAccountName: string | undefined = (
+    req.account as { accountName?: string }
+  )?.accountName;
+
+  if (!creatorAccountName) {
+    throw new UnauthorizedError("Missing creator account name");
+  }
+
+  const subdomain = await DomainService.createDomain(
+    name,
+    [],
+    creatorAccountName,
+    authStrategy,
+    ssoConfig,
+    isVisibleFromOutside,
+  );
+
+  await DomainService.attachSubdomainToDomain(domainName as string, subdomain);
+
+  res.status(200).send();
 };
 
 export const getDomainTOTPQr = async (req: Request, res: Response) => {
-    try {
-        const {domainName, accountName} = req.params;
-        const domain = await Domain.findOne({name: domainName as string}).select(
-            "+totpSecrets",
-        );
-
-        if (!domain) return res.status(404).json({error: "Domain not found"});
-
-        const account = await Account.findOne({name: accountName as string});
-
-        if (!account) return res.status(404).json({error: "Account not found"});
-
-        const qrCodes: Record<string, string> = {};
-        const totpSecrets = domain.toObject().totpSecrets;
-        const accountRolePerDomain = account.memberships.filter(d => d.domainName == domain.name)
-
-        if (accountRolePerDomain.length <= 0 || accountRolePerDomain.length >= 2 || !accountRolePerDomain[0])
-          return res.status(404).json({ error: "Account invalid" });
-
-        for (const [role, secret] of Object.entries(totpSecrets)) {
-            if (!secret || !hasRequiredRole(accountRolePerDomain[0].role, role as Role)) continue;
-            qrCodes[role] = new OTPAuth.TOTP({
-                issuer: "CrowdVision",
-                label: `${domainName} (${role})`,
-                secret: OTPAuth.Secret.fromBase32(secret),
-            }).toString();
-        }
-
-        res.json({qrCodes});
-    } catch (error: any) {
-        res.status(500).json({error: error.message});
-    }
+  const { domainName, accountName } = req.params;
+  const domain = await Domain.findOne({ name: domainName as string }).select(
+    "+totpSecrets",
+  );
+
+  if (!domain) {
+    throw new NotFoundError("Domain not found");
+  }
+
+  const account = await Account.findOne({ name: accountName as string });
+
+  if (!account) {
+    throw new NotFoundError("Account not found");
+  }
+
+  const qrCodes: Record<string, string> = {};
+  const totpSecrets = domain.toObject().totpSecrets;
+  const accountRolePerDomain = account.memberships.filter(
+    (d) => d.domainName == domain.name,
+  );
+
+  if (
+    accountRolePerDomain.length <= 0 ||
+    accountRolePerDomain.length >= 2 ||
+    !accountRolePerDomain[0]
+  ) {
+    throw new NotFoundError("Account role per domain missing");
+  }
+
+  for (const [role, secret] of Object.entries(totpSecrets)) {
+    if (!secret || !hasRequiredRole(accountRolePerDomain[0].role, role as Role))
+      continue;
+    qrCodes[role] = new OTPAuth.TOTP({
+      issuer: "CrowdVision",
+      label: `${domainName} (${role})`,
+      secret: OTPAuth.Secret.fromBase32(secret),
+    }).toString();
+  }
+
+  res.json({ qrCodes });
 };
diff --git a/server/auth-service/src/index.ts b/server/auth-service/src/index.ts
index 579b780..4a937fc 100644
--- a/server/auth-service/src/index.ts
+++ b/server/auth-service/src/index.ts
@@ -6,12 +6,11 @@ import router from "./router.js";
 import { connectMongo } from "./config/db.js";
 import { getClientUrl } from "./config/config.js";
 import cookieParser from "cookie-parser";
+import { globalErrorHandler } from "./middlewares/errorsMiddleware.js";
 
 const PORT = 3000;
 export const app = express();
 
-const swaggerDocument = YAML.load("./openapi.yaml");
-
 app.use(
   cors({
     origin: getClientUrl(),
@@ -30,7 +29,7 @@ app.use(
 );
 
 app.use("/", router);
-app.use("/api-docs", swaggerUi.serve, swaggerUi.setup(swaggerDocument));
+app.use(globalErrorHandler);
 
 if (process.env.NODE_ENV !== "test") {
   connectMongo().then(() => {
diff --git a/server/auth-service/src/middlewares/errorsMiddleware.ts b/server/auth-service/src/middlewares/errorsMiddleware.ts
new file mode 100644
index 0000000..06ff0e5
--- /dev/null
+++ b/server/auth-service/src/middlewares/errorsMiddleware.ts
@@ -0,0 +1,21 @@
+import type { Request, Response, NextFunction } from "express";
+import { BaseError } from "../models/error.js";
+
+export const globalErrorHandler = (
+  err: unknown,
+  _req: Request,
+  res: Response,
+  _next: NextFunction,
+) => {
+  if (err instanceof BaseError) {
+    return res.status(err.code).json({
+      type: err.type,
+      message: err.message,
+    });
+  }
+
+  return res.status(500).json({
+    type: "Internal Server Error",
+    message: "An unexpected error occurred. Please try again later.",
+  });
+};
diff --git a/server/auth-service/src/models/domain.ts b/server/auth-service/src/models/domain.ts
index a603bbc..14081c6 100644
--- a/server/auth-service/src/models/domain.ts
+++ b/server/auth-service/src/models/domain.ts
@@ -1,6 +1,6 @@
 import { Schema, model, Document, Types } from "mongoose";
-import type { Role } from "./roles.js";
-import { ROLE_WEIGHTS } from "./roles.js";
+import type { Role } from "./role.js";
+import { ROLE_WEIGHTS } from "./role.js";
 
 export interface ISSOConfig {
   issuerUrl: string;
diff --git a/server/auth-service/src/models/error.ts b/server/auth-service/src/models/error.ts
new file mode 100644
index 0000000..7c433c7
--- /dev/null
+++ b/server/auth-service/src/models/error.ts
@@ -0,0 +1,48 @@
+export class BaseError extends Error {
+  type: string;
+  code: number;
+  message: string;
+
+  constructor(type: string, code: number, message: string) {
+    super(message);
+    this.type = type;
+    this.code = code;
+    this.message = message;
+  }
+}
+
+export class ValidationError extends BaseError {
+  constructor(message: string) {
+    super("Validation Error", 400 , message);
+  }
+}
+
+export class NotFoundError extends BaseError {
+  constructor(message: string) {
+    super("Not Found Error", 404, message);
+  }
+}
+
+export class InternalError extends BaseError {
+  constructor(message: string) {
+    super("Internal Error", 500, message);
+  }
+}
+
+export class UnauthorizedError extends BaseError {
+  constructor(message: string) {
+    super("Unauthorized Error", 401, message);
+  }
+}
+
+export class ForbiddenError extends BaseError {
+  constructor(message: string) {
+    super("Forbidden Error", 403, message);
+  }
+}
+
+export class ConflictError extends BaseError {
+  constructor(message: string) {
+    super("Conflict Error", 409, message);
+  }
+}
\ No newline at end of file
diff --git a/server/auth-service/src/models/roles.ts b/server/auth-service/src/models/role.ts
similarity index 100%
rename from server/auth-service/src/models/roles.ts
rename to server/auth-service/src/models/role.ts
diff --git a/server/auth-service/src/router.ts b/server/auth-service/src/router.ts
index f2b0cdb..2451ccc 100644
--- a/server/auth-service/src/router.ts
+++ b/server/auth-service/src/router.ts
@@ -21,7 +21,7 @@ import {
   requireHmacSignature,
 } from "./controller/authenticationMiddleware.js";
 import { provideEnterpriseAccount } from "./controller/administrationController.js";
-import { requireAuthorization } from "./models/roles.js";
+import { requireAuthorization } from "./models/role.js";
 
 const router = Router();
 
diff --git a/server/auth-service/src/services/authenticationService.ts b/server/auth-service/src/services/authenticationService.ts
index c8e0f71..a2ac6ed 100644
--- a/server/auth-service/src/services/authenticationService.ts
+++ b/server/auth-service/src/services/authenticationService.ts
@@ -3,7 +3,12 @@ import * as client from "openid-client";
 import { Account } from "../models/account.js";
 import { Domain } from "../models/domain.js";
 import { getClientUrl, getServerUrl } from "../config/config.js";
-import type { Role } from "../models/roles.js";
+import type { Role } from "../models/role.js";
+import {
+  ConflictError,
+  NotFoundError,
+  ValidationError,
+} from "../models/error.js";
 
 export const registerAccount = async (
   accountName: string,
@@ -13,14 +18,15 @@ export const registerAccount = async (
   const account = await Account.findOne({
     $or: [{ email }, { name: accountName }],
   });
+
   if (account) {
-    throw new Error("user already exists");
+    throw new ConflictError("Account with this email or name already exists");
   }
 
   const salt = await bcrypt.genSalt(10);
   const passwordHash = await bcrypt.hash(password, salt);
 
-  return await Account.create({
+  return Account.create({
     name: accountName,
     email,
     password: passwordHash,
@@ -33,13 +39,14 @@ export const authenticateAccount = async (
   password: string,
 ) => {
   const account = await Account.findOne({ name: accountName });
+
   if (!account) {
-    throw new Error("wrong account name");
+    throw new NotFoundError("Account with this name doesn't exist");
   }
 
   const match = await bcrypt.compare(password, account.password);
   if (!match) {
-    throw new Error("wrong password");
+    throw new ValidationError("Invalid password");
   }
 
   return account;
@@ -55,7 +62,7 @@ export const generateSSOLoginUrl = async (
   );
 
   if (!domain || domain.authStrategy !== "oidc" || !domain.ssoConfig) {
-    throw new Error("SSO not configured for this domain");
+    throw new NotFoundError("SSO not configured for this domain");
   }
 
   // Discover IdP
@@ -91,11 +98,14 @@ export const generateSSOLoginUrl = async (
   return redirectUrl.href;
 };
 
-export const processSSOCallback = async (fullUrl: string) => {
+export const processSSOCallback = async (
+  fullUrl: string,
+) => {
   const currentUrl = new URL(fullUrl, getServerUrl());
   const stateParam = currentUrl.searchParams.get("state");
+
   if (!stateParam) {
-    throw new Error("No state returned from provider");
+    throw new ValidationError("Missing state parameter");
   }
 
   // Decode State
@@ -108,7 +118,7 @@ export const processSSOCallback = async (fullUrl: string) => {
     "+ssoConfig.clientSecret",
   );
   if (!domainDoc || !domainDoc.ssoConfig) {
-    throw new Error("Invalid domain config");
+    throw new NotFoundError("Domain or SSO configuration not found");
   }
 
   const serverUrl = new URL(domainDoc.ssoConfig.issuerUrl);
@@ -127,13 +137,15 @@ export const processSSOCallback = async (fullUrl: string) => {
 
   // Map Roles
   const userGroups = claims ? (claims.groups as string[]) || [] : [];
-  const role: Role = userGroups.includes("admin") || userGroups.includes("platform-admin")
-    ? "admin"
-    : userGroups.includes("business-admin") || userGroups.includes("business_admin")
-      ? "business_admin"
-      : userGroups.includes("staff") || userGroups.includes("business-staff")
-        ? "business_staff"
-        : "standard_customer";
+  const role: Role =
+    userGroups.includes("admin") || userGroups.includes("platform-admin")
+      ? "admin"
+      : userGroups.includes("business-admin") ||
+          userGroups.includes("business_admin")
+        ? "business_admin"
+        : userGroups.includes("staff") || userGroups.includes("business-staff")
+          ? "business_staff"
+          : "standard_customer";
 
   // Update Account Membership (Upsert)
   await Account.findOneAndUpdate(
diff --git a/server/auth-service/src/services/domainService.ts b/server/auth-service/src/services/domainService.ts
index 7e8b56b..91d0f84 100644
--- a/server/auth-service/src/services/domainService.ts
+++ b/server/auth-service/src/services/domainService.ts
@@ -1,6 +1,11 @@
-import { Domain, type IDomain, type ISSOConfig } from "../models/domain.js";
+import {
+  Domain,
+  type IDomain,
+  type ISSOConfig,
+} from "../models/domain.js";
 import { Account } from "../models/account.js";
 import { createTOTPForAuthorizedRoles } from "./totpService.js";
+import { ConflictError, NotFoundError } from "../models/error.js";
 
 export const createDomain = async (
   domainName: string,
@@ -13,10 +18,10 @@ export const createDomain = async (
   const domain = await Domain.findOne({ name: domainName });
 
   if (domain) {
-    throw new Error("domain already exists");
+    throw new ConflictError(`Domain with name "${domainName}" already exists`);
   }
 
-  const totpSecrets = await createTOTPForAuthorizedRoles("business_staff")
+  const totpSecrets = await createTOTPForAuthorizedRoles("business_staff");
 
   const createdDomain = await Domain.create({
     name: domainName,
@@ -24,12 +29,16 @@ export const createDomain = async (
     authStrategy: authenticationStrategy,
     ...(authenticationStrategy === "oidc" && ssoConfig ? { ssoConfig } : {}),
     totpSecrets,
-    isVisibleFromOutside
+    isVisibleFromOutside,
   });
 
   await Account.findOneAndUpdate(
     { name: creatorAccountName },
-    { $push: { memberships: { domainName: domainName, role: "business_admin" } } },
+    {
+      $push: {
+        memberships: { domainName: domainName, role: "business_admin" },
+      },
+    },
   );
 
   return createdDomain;
@@ -40,14 +49,16 @@ export const getAllDomains = async () => {
 };
 
 export const getAllAllowedDomains = async () => {
-  return Domain.find({ isVisibleFromOutside: true }).select("-ssoConfig.clientSecret");
-}
+  return Domain.find({ isVisibleFromOutside: true }).select(
+    "-ssoConfig.clientSecret",
+  );
+};
 
 export const getDomainByName = async (domainName: string) => {
   return Domain.findOne({ name: domainName }).select("-ssoConfig.clientSecret");
 };
 
-export const getDomainSubdomains = async (name: string): Promise<string[]> => {
+export const getDomainSubdomains = async (name: string) => {
   const result = await Domain.aggregate([
     { $match: { name } },
     {
@@ -67,24 +78,29 @@ export const getDomainSubdomains = async (name: string): Promise<string[]> => {
     },
   ]);
 
-  if (!result[0]) throw new Error(`Domain "${name}" not found`);
+  if (!result[0]) {
+    throw new NotFoundError(`Domain with name "${name}" not found`);
+  }
 
   return result[0].names ?? [];
 };
 
-export const attachSubdomainToDomain = async (domainName: string, subDomain: IDomain) => {
+export const attachSubdomainToDomain = async (
+  domainName: string,
+  subDomain: IDomain,
+) => {
   const parent = await Domain.findOneAndUpdate(
     { name: domainName },
     { $addToSet: { subdomains: subDomain._id } },
   );
-}
+};
 
 // --- Memberships ---
 export const getAccountMemberships = async (accountName: string) => {
   const account = await Account.findOne({ name: accountName });
 
   if (!account) {
-    throw new Error("account not found");
+    throw new NotFoundError(`Account with name "${accountName}" not found`);
   }
 
   return account.memberships;
@@ -97,11 +113,13 @@ export const subscribeInternal = async (
   const domain = await Domain.findOne({ name: domainName });
 
   if (!domain) {
-    throw new Error("Domain not found");
+    throw new NotFoundError(`Domain with name "${domainName}" not found`);
   }
 
   if (domain.authStrategy === "oidc") {
-    throw new Error("this domain requires SSO login");
+    throw new NotFoundError(
+      `Domain with name "${domainName}" does not support internal subscription`,
+    );
   }
 
   await Account.findOneAndUpdate(
diff --git a/server/auth-service/src/services/tokenService.ts b/server/auth-service/src/services/tokenService.ts
index 447a7e0..0cf2dd7 100644
--- a/server/auth-service/src/services/tokenService.ts
+++ b/server/auth-service/src/services/tokenService.ts
@@ -1,4 +1,4 @@
-import jwt from "jsonwebtoken";
+import jwt, { type JwtPayload } from "jsonwebtoken";
 
 import type {
   DeviceTokenPayload,
@@ -6,18 +6,21 @@ import type {
 } from "../models/token.js";
 import { getTokenSecret } from "../config/config.js";
 import { Account } from "../models/account.js";
+import { InternalError, NotFoundError } from "../models/error.js";
 
-export const generateStandardToken = async (payload: StandardTokenPayload) => {
+export const generateStandardToken = async (
+  payload: StandardTokenPayload,
+) => {
   const secret = getTokenSecret();
 
   if (!secret) {
-    throw new Error("secret configuration error");
+    throw new InternalError("Missing token secrets configuration");
   }
 
-  const account = await Account.findOne({name: payload.accountName});
+  const account = await Account.findOne({ name: payload.accountName });
 
   if (!account) {
-    throw new Error(`Account not found: ${payload.accountName}`);
+    throw new NotFoundError(`Account with name "${payload.accountName}" does not exist`);
   }
 
   return jwt.sign(
@@ -35,7 +38,7 @@ export const generateDeviceToken = (payload: DeviceTokenPayload) => {
   const secret = getTokenSecret();
 
   if (!secret) {
-    throw new Error("secret configuration error");
+    throw new InternalError("Missing token secrets configuration");
   }
 
   return jwt.sign(
@@ -55,7 +58,7 @@ export const verifyToken = (token: string) => {
   const secret = getTokenSecret();
 
   if (!secret) {
-    throw new Error("secret configuration error");
+    throw new InternalError("Missing token secrets configuration");
   }
 
   return jwt.verify(token, secret);
diff --git a/server/auth-service/src/services/totpService.ts b/server/auth-service/src/services/totpService.ts
index fc1bcce..50550ad 100644
--- a/server/auth-service/src/services/totpService.ts
+++ b/server/auth-service/src/services/totpService.ts
@@ -1,32 +1,32 @@
-import { hasRequiredRole, type Role, ROLE_WEIGHTS } from "../models/roles.js";
+import { hasRequiredRole, type Role, ROLE_WEIGHTS } from "../models/role.js";
 import * as OTPAuth from "otpauth";
 import { Domain, type IDomainMembership } from "../models/domain.js";
 import { Account } from "../models/account.js";
 import { Types } from "mongoose";
+import { NotFoundError } from "../models/error.js";
 
-export const resolveRoleFromOTP = async (
-  otp: string,
-) => {
-  try {
-    const domains = await Domain.find().select("+totpSecrets");
+export const resolveRoleFromOTP = async (otp: string) => {
+  const domains = await Domain.find().select("+totpSecrets");
 
-    if (!domains || domains.length <= 0) {
-      return null;
-    }
+  if (!domains || domains.length <= 0) {
+    throw new NotFoundError("Domain or SSO configuration not found");
+  }
 
-    for (const domain of domains) {
-      for (const [role, secret] of Object.entries(domain.totpSecrets)) {
-        const totp = new OTPAuth.TOTP({
-          secret: OTPAuth.Secret.fromBase32(secret),
-        });
-        if (totp.validate({ token: otp, window: 1 }) !== null) {
-          return {domainName: domain.name, role: role as Role} as IDomainMembership;
-        }
+  for (const domain of domains) {
+    for (const [role, secret] of Object.entries(domain.totpSecrets)) {
+      const totp = new OTPAuth.TOTP({
+        secret: OTPAuth.Secret.fromBase32(secret),
+      });
+      if (totp.validate({ token: otp, window: 1 }) !== null) {
+        return {
+          domainName: domain.name,
+          role: role as Role,
+        } as IDomainMembership
       }
     }
-  } catch (error) {
-    return null;
   }
+
+  throw new NotFoundError("Invalid OTP provided");
 };
 
 export const createTOTPForAuthorizedRoles = async (minimumRole: Role) => {
diff --git a/server/notification-service/Dockerfile b/server/notification-service/Dockerfile
index d056500..4fbcbd6 100644
--- a/server/notification-service/Dockerfile
+++ b/server/notification-service/Dockerfile
@@ -10,6 +10,5 @@ WORKDIR /app
 COPY package*.json ./
 RUN npm install --omit=dev
 COPY --from=builder /app/dist ./dist
-COPY --from=builder /app/openapi.yaml ./openapi.yaml
 EXPOSE 3000
 CMD ["npm", "start"]
\ No newline at end of file
diff --git a/server/notification-service/__tests__/globalSetup.cjs b/server/notification-service/__tests__/globalSetup.cjs
new file mode 100644
index 0000000..2c397ca
--- /dev/null
+++ b/server/notification-service/__tests__/globalSetup.cjs
@@ -0,0 +1,19 @@
+/**
+ * Jest globalSetup — runs ONCE before all test suites in the main Jest process.
+ * Starting MongoMemoryServer here instead of inside setupFilesAfterEnv means:
+ *  - Only one MongoDB binary download/start ever happens per test run.
+ *  - No race condition between parallel test files fighting over the lock file.
+ *  - The URI is forwarded to every worker via process.env.
+ */
+const { MongoMemoryServer } = require('mongodb-memory-server');
+
+module.exports = async () => {
+  const mongoServer = await MongoMemoryServer.create();
+
+  // Share the URI with all Jest workers (env vars are inherited by child processes).
+  process.env.MONGO_URI = mongoServer.getUri();
+
+  // Store the instance on `global` so globalTeardown can stop it.
+  // globalSetup and globalTeardown run in the same main process, so `global` is shared.
+  global.__MONGOD__ = mongoServer;
+};
diff --git a/server/notification-service/__tests__/globalTeardown.cjs b/server/notification-service/__tests__/globalTeardown.cjs
new file mode 100644
index 0000000..a3ce78d
--- /dev/null
+++ b/server/notification-service/__tests__/globalTeardown.cjs
@@ -0,0 +1,7 @@
+/**
+ * Jest globalTeardown — runs ONCE after all test suites complete.
+ * Stops the MongoMemoryServer that was started in globalSetup.
+ */
+module.exports = async () => {
+  await global.__MONGOD__?.stop();
+};
diff --git a/server/notification-service/__tests__/notification.test.ts b/server/notification-service/__tests__/notification.test.ts
index 4aa9da3..a5bad9c 100644
--- a/server/notification-service/__tests__/notification.test.ts
+++ b/server/notification-service/__tests__/notification.test.ts
@@ -2,7 +2,7 @@ import { jest } from '@jest/globals';
 import request from 'supertest';
 
 jest.mock('../src/config/redis.js', () => ({
-    connectRedis: jest.fn().mockResolvedValue(true)
+    connectRedis: jest.fn<() => Promise<boolean>>().mockResolvedValue(true)
 }));
 
 jest.mock('../src/services/notificationService.js', () => ({
@@ -72,7 +72,8 @@ describe('Notification Service API', () => {
                 .send({}); // Empty body
 
             expect(res.status).toBe(400);
-            expect(res.body.error).toMatch(/invalid/i);
+            expect(res.body.type).toBeDefined();
+            expect(res.body.message).toBeDefined();
         });
     });
 
diff --git a/server/notification-service/__tests__/setup.ts b/server/notification-service/__tests__/setup.ts
index 7188efc..40730ee 100644
--- a/server/notification-service/__tests__/setup.ts
+++ b/server/notification-service/__tests__/setup.ts
@@ -1,27 +1,26 @@
-import { MongoMemoryServer } from 'mongodb-memory-server';
-import mongoose from 'mongoose';
+import mongoose from "mongoose";
 
-let mongoServer: MongoMemoryServer;
-
-// Increase timeout to 30 seconds for the setup phase
 beforeAll(async () => {
-    mongoServer = await MongoMemoryServer.create();
-    const uri = mongoServer.getUri();
-    process.env.MONGO_URI = uri;
-    await mongoose.connect(uri);
-}, 30000);
+  // Each Jest worker gets its own database within the shared MongoMemoryServer,
+  // so parallel test files can't delete each other's data mid-test.
+  const baseUri = process.env.MONGO_URI!;
+  const dbName = `testdb_worker_${process.env.JEST_WORKER_ID ?? '1'}`;
+  const uri = baseUri.endsWith('/') ? `${baseUri}${dbName}` : `${baseUri}/${dbName}`;
+  await mongoose.connect(uri);
+}, 30_000);
 
 afterEach(async () => {
-    const collections = mongoose.connection.collections;
-    for (const key in collections) {
-        const collection = collections[key];
-        if (collection) {
-            await collection.deleteMany({});
-        }
+  const collections = mongoose.connection.collections;
+  for (const key in collections) {
+    const collection = collections[key];
+    if (collection) {
+      await collection.deleteMany({});
     }
+  }
 });
 
 afterAll(async () => {
-    await mongoose.disconnect();
-    await mongoServer.stop();
+  // Disconnect this worker's mongoose connection.
+  // The MongoMemoryServer itself is stopped by globalTeardown.cjs.
+  await mongoose.disconnect();
 });
\ No newline at end of file
diff --git a/server/notification-service/openapi.yaml b/server/notification-service/openapi.yaml
deleted file mode 100644
index d988d7a..0000000
--- a/server/notification-service/openapi.yaml
+++ /dev/null
@@ -1,122 +0,0 @@
-openapi: 3.1.0
-info:
-  title: Notification Service API
-  description: API for managing push notifications and subscriptions.
-  version: 1.0.0
-servers:
-  - url: http://localhost/notification
-    description: Local gateway endpoint for Notification Service
-paths:
-  /trigger:
-    post:
-      summary: Trigger a manual alert/notification
-      tags:
-        - Notification
-      requestBody:
-        required: false
-        content:
-          application/json:
-            schema:
-              type: object
-              properties:
-                message:
-                  type: string
-                  example: "Emergency in Room 101"
-                type:
-                  type: string
-                  example: "alert"
-      responses:
-        '200':
-          description: Notification sent successfully
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  success:
-                    type: boolean
-                    example: true
-                  message:
-                    type: string
-                    example: "Notification sent to Gateway and Push Service"
-
-  /subscribe:
-    post:
-      summary: Subscribe a client for push notifications
-      tags:
-        - Notification
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              $ref: '#/components/schemas/Subscription'
-      responses:
-        '201':
-          description: Subscribed successfully
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  success:
-                    type: boolean
-                    example: true
-        '400':
-          description: Invalid subscription payload
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-        '500':
-          description: Server error
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-  /public-key:
-    get:
-      summary: Get the VAPID Public Key
-      tags:
-        - Notification
-      responses:
-        '200':
-          description: Public key retrieved successfully
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  publicVapidKey:
-                    type: string
-                    description: The VAPID public key for push notifications
-
-components:
-  schemas:
-    Subscription:
-      type: object
-      required:
-        - endpoint
-        - keys
-      properties:
-        endpoint:
-          type: string
-          format: uri
-          description: The push subscription endpoint URL
-        keys:
-          type: object
-          required:
-            - p256dh
-            - auth
-          properties:
-            p256dh:
-              type: string
-            auth:
-              type: string
\ No newline at end of file
diff --git a/server/notification-service/package.json b/server/notification-service/package.json
index 0cccd64..4d28e71 100644
--- a/server/notification-service/package.json
+++ b/server/notification-service/package.json
@@ -46,6 +46,8 @@
   "jest": {
     "preset": "ts-jest",
     "testEnvironment": "node",
+    "globalSetup": "./__tests__/globalSetup.cjs",
+    "globalTeardown": "./__tests__/globalTeardown.cjs",
     "setupFilesAfterEnv": [
       "./__tests__/setup.ts"
     ],
diff --git a/server/notification-service/src/controller/notificationController.ts b/server/notification-service/src/controller/notificationController.ts
index f2f20dc..a2c33f2 100644
--- a/server/notification-service/src/controller/notificationController.ts
+++ b/server/notification-service/src/controller/notificationController.ts
@@ -1,6 +1,7 @@
 import type { Request, Response } from 'express';
 import { publishNotification } from '../services/notificationService.js';
 import Subscription from '../models/subscription.js'
+import {ValidationError} from "../models/error.js";
 
 export const triggerAlert = async (req: Request, res: Response) => {
     const { message, type } = req.body;
@@ -17,24 +18,17 @@ export const publicKey = async (req: Request, res: Response) => {
 };
 
 export const subscribe = async (req: Request, res: Response) => {
-    try {
-        const subscription = req.body;
-
-        if (!subscription || !subscription.endpoint) {
-            res.status(400).json({ error: 'Invalid subscription payload' });
-            return;
-        }
-
-        await Subscription.findOneAndUpdate(
-            { endpoint: subscription.endpoint },
-            subscription,
-            { upsert: true, returnDocument: 'after' }
-        );
-
-        console.log('✅ Account subscribed successfully');
-        res.status(201).json({ success: true });
-    } catch (error) {
-        console.error('❌ Subscribe Error:', error);
-        res.status(500).json({ error: 'Failed to subscribe' });
+    const subscription = req.body;
+
+    if (!subscription || !subscription.endpoint) {
+        throw new ValidationError("Invalid subscription object received");
     }
+
+    await Subscription.findOneAndUpdate(
+        { endpoint: subscription.endpoint },
+        subscription,
+        { upsert: true, returnDocument: 'after' }
+    );
+
+    res.status(201).json({ success: true });
 };
\ No newline at end of file
diff --git a/server/notification-service/src/index.ts b/server/notification-service/src/index.ts
index 40acb9c..ecbb84b 100644
--- a/server/notification-service/src/index.ts
+++ b/server/notification-service/src/index.ts
@@ -7,14 +7,13 @@ import { connectRedis } from './config/redis.js';
 import { startNotificationLoop } from './services/notificationService.js';
 import {connectMongo} from "./config/db.js";
 import YAML from "yamljs";
+import {globalErrorHandler} from "./middlewares/errorsMiddleware.js";
 
 dotenv.config();
 
 export const app = express();
 const PORT = process.env.PORT || 3000;
 
-const swaggerDocument = YAML.load("./openapi.yaml");
-
 export const getClientUrl = () =>
   process.env.CLIENT_URL || "http://localhost:5173";
 
@@ -27,7 +26,6 @@ app.use(
 app.use(express.json());
 
 app.use('/', router);
-app.use('/api-docs', swaggerUi.serve, swaggerUi.setup(swaggerDocument));
 
 const startServer = async () => {
     await connectRedis();
@@ -42,4 +40,6 @@ const startServer = async () => {
     }
 };
 
+app.use(globalErrorHandler);
+
 startServer();
\ No newline at end of file
diff --git a/server/notification-service/src/middlewares/errorsMiddleware.ts b/server/notification-service/src/middlewares/errorsMiddleware.ts
new file mode 100644
index 0000000..06ff0e5
--- /dev/null
+++ b/server/notification-service/src/middlewares/errorsMiddleware.ts
@@ -0,0 +1,21 @@
+import type { Request, Response, NextFunction } from "express";
+import { BaseError } from "../models/error.js";
+
+export const globalErrorHandler = (
+  err: unknown,
+  _req: Request,
+  res: Response,
+  _next: NextFunction,
+) => {
+  if (err instanceof BaseError) {
+    return res.status(err.code).json({
+      type: err.type,
+      message: err.message,
+    });
+  }
+
+  return res.status(500).json({
+    type: "Internal Server Error",
+    message: "An unexpected error occurred. Please try again later.",
+  });
+};
diff --git a/server/notification-service/src/models/error.ts b/server/notification-service/src/models/error.ts
new file mode 100644
index 0000000..7c433c7
--- /dev/null
+++ b/server/notification-service/src/models/error.ts
@@ -0,0 +1,48 @@
+export class BaseError extends Error {
+  type: string;
+  code: number;
+  message: string;
+
+  constructor(type: string, code: number, message: string) {
+    super(message);
+    this.type = type;
+    this.code = code;
+    this.message = message;
+  }
+}
+
+export class ValidationError extends BaseError {
+  constructor(message: string) {
+    super("Validation Error", 400 , message);
+  }
+}
+
+export class NotFoundError extends BaseError {
+  constructor(message: string) {
+    super("Not Found Error", 404, message);
+  }
+}
+
+export class InternalError extends BaseError {
+  constructor(message: string) {
+    super("Internal Error", 500, message);
+  }
+}
+
+export class UnauthorizedError extends BaseError {
+  constructor(message: string) {
+    super("Unauthorized Error", 401, message);
+  }
+}
+
+export class ForbiddenError extends BaseError {
+  constructor(message: string) {
+    super("Forbidden Error", 403, message);
+  }
+}
+
+export class ConflictError extends BaseError {
+  constructor(message: string) {
+    super("Conflict Error", 409, message);
+  }
+}
\ No newline at end of file
diff --git a/server/notification-service/src/services/notificationService.ts b/server/notification-service/src/services/notificationService.ts
index 29497bd..84c5008 100644
--- a/server/notification-service/src/services/notificationService.ts
+++ b/server/notification-service/src/services/notificationService.ts
@@ -2,24 +2,17 @@ import redisClient from '../config/redis.js';
 import {sendPushToAll} from "./pushService.js";
 
 export const publishNotification = async (message: string, type: string = 'info') => {
-    try {
-        const payload = {
-            id: Date.now().toString(),
-            message,
-            type,
-            timestamp: new Date()
-        };
+    const payload = {
+        id: Date.now().toString(),
+        message,
+        type,
+        timestamp: new Date()
+    };
 
-        await redisClient.publish('notifications', JSON.stringify(payload));
-        console.log(`📤 Published: ${message}`);
-    } catch (error) {
-        console.error('Error publishing notification:', error);
-    }
+    await redisClient.publish('notifications', JSON.stringify(payload));
 };
 
 export const startNotificationLoop = () => {
-    console.log('⏰ Starting 10-second notification loop...');
-
     setInterval(async () => {
         await publishNotification(`System Status Check: ${new Date().toLocaleTimeString()}`, 'info');
         await sendPushToAll({ title: 'Critical Alert', message: "HALLO" })
diff --git a/server/notification-service/src/services/pushService.ts b/server/notification-service/src/services/pushService.ts
index fecb8d9..d9a2640 100644
--- a/server/notification-service/src/services/pushService.ts
+++ b/server/notification-service/src/services/pushService.ts
@@ -1,5 +1,6 @@
 import webpush from 'web-push';
 import Subscription from '../models/subscription.js';
+import {NotFoundError} from "../models/error.js";
 
 const publicVapidKey = process.env.VAPID_PUBLIC_KEY || ''
 const privateVapidKey = process.env.VAPID_PRIVATE_KEY || ''
@@ -19,8 +20,7 @@ export const sendPushToAll = async (payload: any) => {
     const subscriptions = await Subscription.find();
 
     if (subscriptions.length === 0) {
-        console.log('⚠️ No users subscribed! (Check DB connection or collection name)');
-        return;
+        throw new NotFoundError("No subscriptions found to send notifications to.");
     }
 
     const notificationPayload = JSON.stringify({
diff --git a/server/socket-service/Dockerfile b/server/socket-service/Dockerfile
index d056500..4fbcbd6 100644
--- a/server/socket-service/Dockerfile
+++ b/server/socket-service/Dockerfile
@@ -10,6 +10,5 @@ WORKDIR /app
 COPY package*.json ./
 RUN npm install --omit=dev
 COPY --from=builder /app/dist ./dist
-COPY --from=builder /app/openapi.yaml ./openapi.yaml
 EXPOSE 3000
 CMD ["npm", "start"]
\ No newline at end of file
diff --git a/server/socket-service/openapi.yaml b/server/socket-service/openapi.yaml
deleted file mode 100644
index b89ee27..0000000
--- a/server/socket-service/openapi.yaml
+++ /dev/null
@@ -1,184 +0,0 @@
-openapi: 3.1.0
-info:
-  title: Auth Service API
-  description: API for user authentication and domain management.
-  version: 1.0.0
-servers:
-  - url: http://localhost:80/auth/
-    description: Local development server
-paths:
-  /register:
-    post:
-      summary: Register a new user
-      tags:
-        - Auth
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              type: object
-              properties:
-                username:
-                  type: string
-                  example: "jdoe"
-                email:
-                  type: string
-                  format: email
-                  example: "jdoe@example.com"
-                password:
-                  type: string
-                  format: password
-                  example: "securePassword123"
-      responses:
-        '201':
-          description: Account created successfully
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  message:
-                    type: string
-                    example: "Account created"
-                  userId:
-                    type: string
-                    example: "60d5ecb8b392d7001f8e4b5a"
-                  username:
-                    type: string
-                    example: "jdoe"
-        '400':
-          description: Bad request
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-  /login:
-    post:
-      summary: Login a user
-      tags:
-        - Auth
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              type: object
-              properties:
-                username:
-                  type: string
-                  example: "jdoe"
-                password:
-                  type: string
-                  format: password
-                  example: "securePassword123"
-      responses:
-        '200':
-          description: Login successful
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  message:
-                    type: string
-                    example: "Login successful"
-                  userId:
-                    type: string
-                    example: "60d5ecb8b392d7001f8e4b5a"
-                  username:
-                    type: string
-                    example: "jdoe"
-        '400':
-          description: Invalid credentials or error
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-  /domain/{username}:
-    get:
-      summary: Get user domain information
-      tags:
-        - Domain
-      parameters:
-        - in: path
-          name: username
-          schema:
-            type: string
-          required: true
-          description: The username to fetch the domain for
-      responses:
-        '200':
-          description: Account domain retrieved successfully
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  domain:
-                    $ref: '#/components/schemas/Domain'
-        '400':
-          description: Error retrieving domain
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-  /domain/level/{username}:
-    get:
-      summary: Get user domain level
-      tags:
-        - Domain
-      parameters:
-        - in: path
-          name: username
-          schema:
-            type: string
-          required: true
-          description: The username to fetch the domain level for
-      responses:
-        '200':
-          description: Domain level retrieved successfully
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  domainLevel:
-                    type: string # Assuming string or number based on context
-                    description: The level associated with the user's domain
-        '400':
-          description: Error retrieving domain level
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-components:
-  schemas:
-    Domain:
-      type: object
-      properties:
-        name:
-          type: string
-          example: "crowd-vision"
-        subdomain:
-          type: string
-          example: "analytics"
-      required:
-        - name
-  
diff --git a/server/twin-service/Dockerfile b/server/twin-service/Dockerfile
index d056500..4fbcbd6 100644
--- a/server/twin-service/Dockerfile
+++ b/server/twin-service/Dockerfile
@@ -10,6 +10,5 @@ WORKDIR /app
 COPY package*.json ./
 RUN npm install --omit=dev
 COPY --from=builder /app/dist ./dist
-COPY --from=builder /app/openapi.yaml ./openapi.yaml
 EXPOSE 3000
 CMD ["npm", "start"]
\ No newline at end of file
diff --git a/server/twin-service/__tests__/globalSetup.cjs b/server/twin-service/__tests__/globalSetup.cjs
new file mode 100644
index 0000000..2c397ca
--- /dev/null
+++ b/server/twin-service/__tests__/globalSetup.cjs
@@ -0,0 +1,19 @@
+/**
+ * Jest globalSetup — runs ONCE before all test suites in the main Jest process.
+ * Starting MongoMemoryServer here instead of inside setupFilesAfterEnv means:
+ *  - Only one MongoDB binary download/start ever happens per test run.
+ *  - No race condition between parallel test files fighting over the lock file.
+ *  - The URI is forwarded to every worker via process.env.
+ */
+const { MongoMemoryServer } = require('mongodb-memory-server');
+
+module.exports = async () => {
+  const mongoServer = await MongoMemoryServer.create();
+
+  // Share the URI with all Jest workers (env vars are inherited by child processes).
+  process.env.MONGO_URI = mongoServer.getUri();
+
+  // Store the instance on `global` so globalTeardown can stop it.
+  // globalSetup and globalTeardown run in the same main process, so `global` is shared.
+  global.__MONGOD__ = mongoServer;
+};
diff --git a/server/twin-service/__tests__/globalTeardown.cjs b/server/twin-service/__tests__/globalTeardown.cjs
new file mode 100644
index 0000000..a3ce78d
--- /dev/null
+++ b/server/twin-service/__tests__/globalTeardown.cjs
@@ -0,0 +1,7 @@
+/**
+ * Jest globalTeardown — runs ONCE after all test suites complete.
+ * Stops the MongoMemoryServer that was started in globalSetup.
+ */
+module.exports = async () => {
+  await global.__MONGOD__?.stop();
+};
diff --git a/server/twin-service/__tests__/setup.ts b/server/twin-service/__tests__/setup.ts
index f26f94e..40730ee 100644
--- a/server/twin-service/__tests__/setup.ts
+++ b/server/twin-service/__tests__/setup.ts
@@ -1,26 +1,26 @@
-import { MongoMemoryServer } from 'mongodb-memory-server';
-import mongoose from 'mongoose';
-
-let mongoServer: MongoMemoryServer;
+import mongoose from "mongoose";
 
 beforeAll(async () => {
-    mongoServer = await MongoMemoryServer.create();
-    const uri = mongoServer.getUri();
-    process.env.MONGO_URI = uri;
-    await mongoose.connect(uri);
-});
+  // Each Jest worker gets its own database within the shared MongoMemoryServer,
+  // so parallel test files can't delete each other's data mid-test.
+  const baseUri = process.env.MONGO_URI!;
+  const dbName = `testdb_worker_${process.env.JEST_WORKER_ID ?? '1'}`;
+  const uri = baseUri.endsWith('/') ? `${baseUri}${dbName}` : `${baseUri}/${dbName}`;
+  await mongoose.connect(uri);
+}, 30_000);
 
 afterEach(async () => {
-    const collections = mongoose.connection.collections;
-    for (const key in collections) {
-        const collection = collections[key];
-        if (collection) {
-            await collection.deleteMany({});
-        }
+  const collections = mongoose.connection.collections;
+  for (const key in collections) {
+    const collection = collections[key];
+    if (collection) {
+      await collection.deleteMany({});
     }
+  }
 });
 
 afterAll(async () => {
-    await mongoose.disconnect();
-    await mongoServer.stop();
+  // Disconnect this worker's mongoose connection.
+  // The MongoMemoryServer itself is stopped by globalTeardown.cjs.
+  await mongoose.disconnect();
 });
\ No newline at end of file
diff --git a/server/twin-service/__tests__/twin.test.ts b/server/twin-service/__tests__/twin.test.ts
index d6684e7..2cd782b 100644
--- a/server/twin-service/__tests__/twin.test.ts
+++ b/server/twin-service/__tests__/twin.test.ts
@@ -41,8 +41,8 @@ describe('Twin Service API', () => {
                 .post('/register')
                 .send(mockBuilding);
 
-            expect(res.status).toBe(400);
-            expect(res.body.error).toMatch(/exists/i);
+            expect(res.status).toBe(409);
+            expect(res.body.type).toBeDefined();
         });
     });
 
@@ -104,12 +104,12 @@ describe('Twin Service API', () => {
             expect(room?.capacity).toBe(50);
         });
 
-        it('should return 400 if building not found', async () => {
+        it('should return 404 if building not found', async () => {
             const res = await request(app)
                 .patch('/building/FAKE_BUILDING/room/Room-101')
                 .send({ capacity: 50 });
 
-            expect(res.status).toBe(400);
+            expect(res.status).toBe(404);
         });
 
         it('should return 400 if room not found', async () => {
@@ -117,8 +117,9 @@ describe('Twin Service API', () => {
                 .patch(`/building/${mockBuilding.id}/room/FAKE_ROOM`)
                 .send({ capacity: 50 });
 
-            expect(res.status).toBe(400);
-            expect(res.body.error).toMatch(/room not found/i);
+            expect(res.status).toBe(404);
+            expect(res.body.type).toBeDefined();
+            expect(res.body.message.toLowerCase()).toContain("room");
         });
     });
 });
\ No newline at end of file
diff --git a/server/twin-service/openapi.yaml b/server/twin-service/openapi.yaml
deleted file mode 100644
index e4d1218..0000000
--- a/server/twin-service/openapi.yaml
+++ /dev/null
@@ -1,225 +0,0 @@
-openapi: 3.1.0
-info:
-  title: Twin Service API
-  description: API for managing digital twins of buildings and rooms.
-  version: 1.0.0
-servers:
-  - url: http://localhost/twin
-    description: Local gateway endpoint for Twin Service
-paths:
-  /register:
-    post:
-      summary: Register a new building
-      tags:
-        - Twin
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              $ref: '#/components/schemas/BuildingInput'
-      responses:
-        '201':
-          description: Building registered successfully
-          content:
-            application/json:
-              schema:
-                $ref: '#/components/schemas/Building'
-        '400':
-          description: Bad request
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-  /building/{id}:
-    get:
-      summary: Get a building by ID
-      tags:
-        - Twin
-      parameters:
-        - in: path
-          name: id
-          schema:
-            type: string
-          required: true
-          description: The unique identifier of the building
-      responses:
-        '200':
-          description: Building retrieved successfully
-          content:
-            application/json:
-              schema:
-                $ref: '#/components/schemas/Building'
-        '404':
-          description: Building not found
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-  /buildings/{domain}:
-    get:
-      summary: Get buildings by domain
-      tags:
-        - Twin
-      parameters:
-        - in: path
-          name: domain
-          schema:
-            type: string
-          required: true
-          description: The domain associated with the buildings
-      responses:
-        '200':
-          description: List of buildings retrieved successfully
-          content:
-            application/json:
-              schema:
-                type: array
-                items:
-                  $ref: '#/components/schemas/Building'
-        '404':
-          description: Error retrieving buildings
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-  /building/{buildingId}/room/{roomId}:
-    patch:
-      summary: Update a room within a building
-      tags:
-        - Twin
-      parameters:
-        - in: path
-          name: buildingId
-          schema:
-            type: string
-          required: true
-          description: The ID of the building
-        - in: path
-          name: roomId
-          schema:
-            type: string
-          required: true
-          description: The ID of the room to update
-      requestBody:
-        required: true
-        content:
-          application/json:
-            schema:
-              type: object
-              description: Fields to update in the room (e.g., temperature, no_person, color)
-              example:
-                temperature: 24.5
-                no_person: 5
-                color: "#ff0000"
-      responses:
-        '200':
-          description: Room updated successfully
-          content:
-            application/json:
-              schema:
-                $ref: '#/components/schemas/Room'
-        '400':
-          description: Error updating room
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  error:
-                    type: string
-
-components:
-  schemas:
-    Coordinates:
-      type: object
-      required:
-        - x
-        - y
-        - z
-      properties:
-        x:
-          type: number
-        y:
-          type: number
-        z:
-          type: number
-
-    Dimensions:
-      type: object
-      required:
-        - width
-        - height
-        - depth
-      properties:
-        width:
-          type: number
-        height:
-          type: number
-        depth:
-          type: number
-
-    Room:
-      type: object
-      required:
-        - id
-        - capacity
-        - position
-        - dimensions
-      properties:
-        id:
-          type: string
-        capacity:
-          type: number
-        position:
-          $ref: '#/components/schemas/Coordinates'
-        dimensions:
-          $ref: '#/components/schemas/Dimensions'
-        color:
-          type: string
-        temperature:
-          type: number
-        no_person:
-          type: number
-
-    BuildingInput:
-      type: object
-      required:
-        - id
-        - rooms
-        - domains
-      properties:
-        id:
-          type: string
-        rooms:
-          type: array
-          items:
-            $ref: '#/components/schemas/Room'
-        domains:
-          type: array
-          items:
-            type: string
-
-    Building:
-      allOf:
-        - $ref: '#/components/schemas/BuildingInput'
-        - type: object
-          properties:
-            createdAt:
-              type: string
-              format: date-time
-            updatedAt:
-              type: string
-              format: date-time
\ No newline at end of file
diff --git a/server/twin-service/package.json b/server/twin-service/package.json
index df8b7b3..3f3acb7 100644
--- a/server/twin-service/package.json
+++ b/server/twin-service/package.json
@@ -41,6 +41,8 @@
   "jest": {
     "preset": "ts-jest",
     "testEnvironment": "node",
+    "globalSetup": "./__tests__/globalSetup.cjs",
+    "globalTeardown": "./__tests__/globalTeardown.cjs",
     "setupFilesAfterEnv": [
       "./__tests__/setup.ts"
     ],
diff --git a/server/twin-service/src/controller/twinController.ts b/server/twin-service/src/controller/twinController.ts
index 5f1edd0..886ce1d 100644
--- a/server/twin-service/src/controller/twinController.ts
+++ b/server/twin-service/src/controller/twinController.ts
@@ -7,42 +7,26 @@ import {
 } from "../services/twinService.js";
 
 export const register = async (req: Request, res: Response) => {
-    try {
-        const { id, rooms, domains } = req.body;
-        const building = await registerBuilding(id, rooms, domains);
-        res.status(201).json(building);
-    } catch (error: any) {
-        res.status(400).json({ error: error.message });
-    }
+    const { id, rooms, domains } = req.body;
+    const building = await registerBuilding(id, rooms, domains);
+    res.status(201).json(building);
 };
 
 export const getById = async (req: Request, res: Response) => {
-    try {
-        const id = req.params.id;
-        const building = await getBuildingById(id as string);
-        res.status(200).json(building);
-    } catch (error: any) {
-        res.status(404).json({ error: error.message });
-    }
+    const id = req.params.id;
+    const building = await getBuildingById(id as string);
+    res.status(200).json(building);
 };
 
 export const getByDomain = async (req: Request, res: Response) => {
-    try {
-        const domain = req.params.domain;
-        const buildings = await getBuildingsByDomain(domain as string);
-        res.status(200).json(buildings);
-    } catch (error: any) {
-        res.status(404).json({ error: error.message });
-    }
+    const domain = req.params.domain;
+    const buildings = await getBuildingsByDomain(domain as string);
+    res.status(200).json(buildings);
 };
 
 export const updateRoom = async (req: Request, res: Response) => {
-    try {
-        const { buildingId, roomId } = req.params;
-        const updates = req.body;
-        const updatedRoom = await updateRoomInBuilding(buildingId as string, roomId as string, updates);
-        res.status(200).json(updatedRoom);
-    } catch (error: any) {
-        res.status(400).json({ error: error.message });
-    }
+    const { buildingId, roomId } = req.params;
+    const updates = req.body;
+    const updatedRoom = await updateRoomInBuilding(buildingId as string, roomId as string, updates);
+    res.status(200).json(updatedRoom);
 }
\ No newline at end of file
diff --git a/server/twin-service/src/index.ts b/server/twin-service/src/index.ts
index 649cf38..91cee4e 100644
--- a/server/twin-service/src/index.ts
+++ b/server/twin-service/src/index.ts
@@ -4,11 +4,11 @@ import swaggerUi from 'swagger-ui-express';
 import YAML from "yamljs";
 import router from "./router.js";
 import {connectMongo} from "./config/db.js";
+import {globalErrorHandler} from "./middlewares/errorsMiddleware.js";
 
 const PORT = 3000;
 export const app = express()
 
-const swaggerDocument = YAML.load("./openapi.yaml");
 export const getClientUrl = () =>
   process.env.CLIENT_URL || "http://localhost:5173";
 
@@ -20,7 +20,7 @@ app.use(
 );
 app.use(express.json());
 app.use('/', router);
-app.use('/api-docs', swaggerUi.serve, swaggerUi.setup(swaggerDocument));
+app.use(globalErrorHandler);
 
 if (process.env.NODE_ENV !== 'test') {
     connectMongo().then(() => {
diff --git a/server/twin-service/src/middlewares/errorsMiddleware.ts b/server/twin-service/src/middlewares/errorsMiddleware.ts
new file mode 100644
index 0000000..06ff0e5
--- /dev/null
+++ b/server/twin-service/src/middlewares/errorsMiddleware.ts
@@ -0,0 +1,21 @@
+import type { Request, Response, NextFunction } from "express";
+import { BaseError } from "../models/error.js";
+
+export const globalErrorHandler = (
+  err: unknown,
+  _req: Request,
+  res: Response,
+  _next: NextFunction,
+) => {
+  if (err instanceof BaseError) {
+    return res.status(err.code).json({
+      type: err.type,
+      message: err.message,
+    });
+  }
+
+  return res.status(500).json({
+    type: "Internal Server Error",
+    message: "An unexpected error occurred. Please try again later.",
+  });
+};
diff --git a/server/twin-service/src/models/error.ts b/server/twin-service/src/models/error.ts
new file mode 100644
index 0000000..7c433c7
--- /dev/null
+++ b/server/twin-service/src/models/error.ts
@@ -0,0 +1,48 @@
+export class BaseError extends Error {
+  type: string;
+  code: number;
+  message: string;
+
+  constructor(type: string, code: number, message: string) {
+    super(message);
+    this.type = type;
+    this.code = code;
+    this.message = message;
+  }
+}
+
+export class ValidationError extends BaseError {
+  constructor(message: string) {
+    super("Validation Error", 400 , message);
+  }
+}
+
+export class NotFoundError extends BaseError {
+  constructor(message: string) {
+    super("Not Found Error", 404, message);
+  }
+}
+
+export class InternalError extends BaseError {
+  constructor(message: string) {
+    super("Internal Error", 500, message);
+  }
+}
+
+export class UnauthorizedError extends BaseError {
+  constructor(message: string) {
+    super("Unauthorized Error", 401, message);
+  }
+}
+
+export class ForbiddenError extends BaseError {
+  constructor(message: string) {
+    super("Forbidden Error", 403, message);
+  }
+}
+
+export class ConflictError extends BaseError {
+  constructor(message: string) {
+    super("Conflict Error", 409, message);
+  }
+}
\ No newline at end of file
diff --git a/server/twin-service/src/services/twinService.ts b/server/twin-service/src/services/twinService.ts
index a30307a..da8337b 100644
--- a/server/twin-service/src/services/twinService.ts
+++ b/server/twin-service/src/services/twinService.ts
@@ -1,9 +1,10 @@
 import {Building, type Room} from "../models/twin.js";
+import {ConflictError, NotFoundError} from "../models/error.js";
 
 
 export const registerBuilding = async (id: string, rooms: any, domains: string[]) => {
     if (await Building.findOne({ id })) {
-        throw new Error("Building already exists");
+        throw new ConflictError(`Building with id: "${id}" already exists`);
     }
 
     const building = new Building({ id, rooms, domains });
@@ -15,7 +16,7 @@ export const getBuildingById = async (id: string) => {
     const building = await Building.findOne({ id });
 
     if (!building) {
-        throw new Error("Building not found");
+        throw new NotFoundError(`Building with id: "${id}" not found`);
     }
     return building;
 };
@@ -24,17 +25,18 @@ export const getBuildingsByDomain = async (domain: string) => {
     const buildings = await Building.find({ domains: domain });
 
     if (buildings.length === 0) {
-        throw new Error("No buildings found for the specified domain");
+        throw new NotFoundError(`Building within the domain: "${domain}" not found`);
     }
     return buildings;
 };
 
 export const updateRoomInBuilding = async (buildingId: string, roomId: string, updates: Partial<Room>) => {
-    const building = await Building.findOne({ id: buildingId });
-    if (!building) throw new Error("Building not found");
+    const building = await getBuildingById(buildingId);
 
     const room = building.rooms.find(r => r.id === roomId);
-    if (!room) throw new Error("Room not found");
+    if (!room) {
+        throw new NotFoundError(`Room with id "${roomId}" in the building "${buildingId}" not found`);
+    }
 
     if (updates.id !== undefined) room.id = updates.id;
     if (updates.color !== undefined) room.color = updates.color;