diff --git a/Sources/NextcloudKit/NKCommon.swift b/Sources/NextcloudKit/NKCommon.swift
index 73a2c71c..8d491659 100644
--- a/Sources/NextcloudKit/NKCommon.swift
+++ b/Sources/NextcloudKit/NKCommon.swift
@@ -66,6 +66,12 @@ public struct NKCommon: Sendable {
 
     public let notificationCenterChunkedFileStop = NSNotification.Name(rawValue: "NextcloudKit.chunkedFile.stop")
 
+    public let headerAccount = "X-NC-Account"
+    public let headerCheckInterceptor = "X-NC-CheckInterceptor"
+    public let groupDefaultsUnauthorized = "Unauthorized"
+    public let groupDefaultsUnavailable = "Unavailable"
+    public let groupDefaultsToS = "ToS"
+
     public enum TypeReachability: Int {
         case unknown = 0
         case notReachable = 1
@@ -432,6 +438,40 @@ public struct NKCommon: Sendable {
         return completion(filesChunk)
     }
 
+    // MARK: - Server Error GroupDefaults
+
+    public func appendServerErrorAccount(_ account: String, errorCode: Int) {
+        guard let groupDefaults = UserDefaults(suiteName: groupIdentifier) else {
+            return
+        }
+
+        /// Unavailable
+        if errorCode == 503 {
+            var array = groupDefaults.array(forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsUnavailable) as? [String] ?? []
+
+            if !array.contains(account) {
+                array.append(account)
+                groupDefaults.set(array, forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsUnavailable)
+            }
+        /// Unauthorized
+        } else if errorCode == 401 {
+            var array = groupDefaults.array(forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsUnauthorized) as? [String] ?? []
+
+            if !array.contains(account) {
+                array.append(account)
+                groupDefaults.set(array, forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsUnauthorized)
+            }
+        /// ToS
+        } else if errorCode == 403 {
+            var array = groupDefaults.array(forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsToS) as? [String] ?? []
+
+            if !array.contains(account) {
+                array.append(account)
+                groupDefaults.set(array, forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsToS)
+            }
+        }
+    }
+
     // MARK: - Common
 
     public func getSession(account: String) -> NKSession? {
@@ -444,7 +484,7 @@ public struct NKCommon: Sendable {
         return session
     }
 
-    public func getStandardHeaders(account: String, checkUnauthorized: Bool? = nil, options: NKRequestOptions? = nil) -> HTTPHeaders? {
+    public func getStandardHeaders(account: String, options: NKRequestOptions? = nil) -> HTTPHeaders? {
         guard let session = nksessions.filter({ $0.account == account }).first else { return nil}
         var headers: HTTPHeaders = []
 
@@ -465,9 +505,9 @@ public struct NKCommon: Sendable {
         for (key, value) in options?.customHeader ?? [:] {
             headers.update(name: key, value: value)
         }
-        headers.update(name: "X-NC-Account", value: account)
-        if let checkUnauthorized {
-            headers.update(name: "X-NC-CheckUnauthorized", value: checkUnauthorized.description)
+        headers.update(name: headerAccount, value: account)
+        if let checkInterceptor = options?.checkInterceptor {
+            headers.update(name: headerCheckInterceptor, value: checkInterceptor.description)
         }
         // Paginate
         if let options {
diff --git a/Sources/NextcloudKit/NKDataFileXML.swift b/Sources/NextcloudKit/NKDataFileXML.swift
index 268b3d20..bafb99cd 100644
--- a/Sources/NextcloudKit/NKDataFileXML.swift
+++ b/Sources/NextcloudKit/NKDataFileXML.swift
@@ -6,7 +6,7 @@
 import Foundation
 import SwiftyXMLParser
 
-class NKDataFileXML: NSObject {
+public class NKDataFileXML: NSObject {
     var nkCommonInstance: NKCommon
     let requestBodyComments =
     """
@@ -51,7 +51,7 @@ class NKDataFileXML: NSObject {
     </d:propertyupdate>
     """
 
-    func getRequestBodyFile(createProperties: [NKProperties]?, removeProperties: [NKProperties] = []) -> String {
+    public func getRequestBodyFile(createProperties: [NKProperties]?, removeProperties: [NKProperties] = []) -> String {
         let request = """
         <?xml version=\"1.0\" encoding=\"UTF-8\"?>
         <d:propfind xmlns:d=\"DAV:\" xmlns:oc=\"http://owncloud.org/ns\" xmlns:nc=\"http://nextcloud.org/ns\">
@@ -63,6 +63,20 @@ class NKDataFileXML: NSObject {
         return request
     }
 
+    public func getRequestBodyFileExists() -> String {
+        let request = """
+        <?xml version=\"1.0\" encoding=\"UTF-8\"?>
+        <d:propfind xmlns:d=\"DAV:\" xmlns:oc=\"http://owncloud.org/ns\" xmlns:nc=\"http://nextcloud.org/ns\">
+            <d:prop>
+                <d:getetag />
+                <fileid xmlns=\"http://owncloud.org/ns\"/>
+                <id xmlns=\"http://owncloud.org/ns\"/>
+            </d:prop>
+        </d:propfind>
+        """
+        return request
+    }
+
     let requestBodyFileSetFavorite =
     """
     <?xml version=\"1.0\"?>
@@ -229,7 +243,7 @@ class NKDataFileXML: NSObject {
     </d:propertyupdate>
     """
 
-    init(nkCommonInstance: NKCommon) {
+    public init(nkCommonInstance: NKCommon) {
         self.nkCommonInstance = nkCommonInstance
         super.init()
     }
diff --git a/Sources/NextcloudKit/NKError.swift b/Sources/NextcloudKit/NKError.swift
index 5d4db76d..67ab4b09 100644
--- a/Sources/NextcloudKit/NKError.swift
+++ b/Sources/NextcloudKit/NKError.swift
@@ -52,6 +52,10 @@ public struct NKError: Sendable, Equatable {
     public static let xmlError = NKError(errorCode: NSURLErrorBadServerResponse, errorDescription: NSLocalizedString("_error_decode_xml_", value: "Invalid response, error decoding XML", comment: ""))
     public static let invalidDate = NKError(errorCode: NSURLErrorBadServerResponse, errorDescription: NSLocalizedString("_invalid_date_format_", value: "Invalid date format", comment: ""))
     public static let invalidData = NKError(errorCode: NSURLErrorCannotDecodeContentData, errorDescription: NSLocalizedString("_invalid_data_format_", value: "Invalid data format", comment: ""))
+    public static let unauthorizedError = NKError(errorCode: 401, errorDescription: NSLocalizedString("_unauthorized_", value: "Unauthorized", comment: ""))
+    public static let unavailableError = NKError(errorCode: 503, errorDescription: NSLocalizedString("_Unavailable_", value: "Unavailable", comment: ""))
+    public static let forbiddenError = NKError(errorCode: 403, errorDescription: NSLocalizedString("_forbidden_", value: "Forbidden", comment: ""))
+
     public static let success = NKError(errorCode: 0, errorDescription: "")
 
     public static func getErrorDescription(for code: Int) -> String? {
diff --git a/Sources/NextcloudKit/NKInterceptor.swift b/Sources/NextcloudKit/NKInterceptor.swift
index 795c23cb..394748b3 100644
--- a/Sources/NextcloudKit/NKInterceptor.swift
+++ b/Sources/NextcloudKit/NKInterceptor.swift
@@ -13,24 +13,37 @@ final class NKInterceptor: RequestInterceptor, Sendable {
     }
 
     func adapt(_ urlRequest: URLRequest, for session: Session, completion: @escaping (Result<URLRequest, Error>) -> Void) {
-        //
-        // Detect if exists in the groupDefaults Unauthorized array the account
-        //
         if let url: String = urlRequest.url?.absoluteString,
            self.nkCommonInstance.levelLog > 0 {
             debugPrint("[DEBUG] Interceptor request url: " + url)
         }
 
-        if let checkUnauthorized = urlRequest.value(forHTTPHeaderField: "X-NC-CheckUnauthorized"),
-           checkUnauthorized == "false" {
+        if let checkInterceptor = urlRequest.value(forHTTPHeaderField: nkCommonInstance.headerCheckInterceptor),
+           checkInterceptor == "false" {
             return completion(.success(urlRequest))
-        } else if let account = urlRequest.value(forHTTPHeaderField: "X-NC-Account"),
-                  let groupDefaults = UserDefaults(suiteName: NextcloudKit.shared.nkCommonInstance.groupIdentifier),
-                  let unauthorizedArray = groupDefaults.array(forKey: "Unauthorized") as? [String],
-                  unauthorizedArray.contains(account) {
-            self.nkCommonInstance.writeLog("[DEBUG] Unauthorized for account: \(account)")
-            let error = AFError.responseValidationFailed(reason: .unacceptableStatusCode(code: 401))
-            return completion(.failure(error))
+        }
+
+        if let account = urlRequest.value(forHTTPHeaderField: nkCommonInstance.headerAccount),
+           let groupDefaults = UserDefaults(suiteName: nkCommonInstance.groupIdentifier) {
+            /// Unauthorized
+            if let array = groupDefaults.array(forKey: nkCommonInstance.groupDefaultsUnauthorized) as? [String],
+               array.contains(account) {
+                self.nkCommonInstance.writeLog("[DEBUG] Unauthorized for account: \(account)")
+                let error = AFError.responseValidationFailed(reason: .unacceptableStatusCode(code: 401))
+                return completion(.failure(error))
+            /// Unavailable
+            } else if let array = groupDefaults.array(forKey: nkCommonInstance.groupDefaultsUnavailable) as? [String],
+                      array.contains(account) {
+                self.nkCommonInstance.writeLog("[DEBUG] Unavailable for account: \(account)")
+                let error = AFError.responseValidationFailed(reason: .unacceptableStatusCode(code: 503))
+                return completion(.failure(error))
+            /// ToS
+            } else if let array = groupDefaults.array(forKey: nkCommonInstance.groupDefaultsToS) as? [String],
+                      array.contains(account) {
+                self.nkCommonInstance.writeLog("[DEBUG] ToS for account: \(account)")
+                let error = AFError.responseValidationFailed(reason: .unacceptableStatusCode(code: 403))
+                return completion(.failure(error))
+            }
         }
 
         completion(.success(urlRequest))
diff --git a/Sources/NextcloudKit/NKMonitor.swift b/Sources/NextcloudKit/NKMonitor.swift
index a0575297..ac650ef4 100644
--- a/Sources/NextcloudKit/NKMonitor.swift
+++ b/Sources/NextcloudKit/NKMonitor.swift
@@ -28,44 +28,14 @@ final class NKMonitor: EventMonitor, Sendable {
     func request<Value>(_ request: DataRequest, didParseResponse response: AFDataResponse<Value>) {
         nkCommonInstance.delegate?.request(request, didParseResponse: response)
 
-        if let statusCode = response.response?.statusCode {
-
-            //
-            // Unauthorized, append the account in groupDefaults unauthorized array
-            //
-            if statusCode == 401,
-               let headerValue = request.request?.allHTTPHeaderFields?["X-NC-CheckUnauthorized"],
-               headerValue.lowercased() == "true",
-               let account = request.request?.allHTTPHeaderFields?["X-NC-Account"] as? String,
-               let groupDefaults = UserDefaults(suiteName: NextcloudKit.shared.nkCommonInstance.groupIdentifier) {
-
-                var unauthorizedArray = groupDefaults.array(forKey: "Unauthorized") as? [String] ?? []
-                if !unauthorizedArray.contains(account) {
-                    unauthorizedArray.append(account)
-                    groupDefaults.set(unauthorizedArray, forKey: "Unauthorized")
-                    groupDefaults.synchronize()
-                }
-
-            //
-            // Unavailable, append the account in groupDefaults unavailable array
-            //
-            } else if statusCode == 503,
-                      let account = request.request?.allHTTPHeaderFields?["X-NC-Account"] as? String,
-                      let groupDefaults = UserDefaults(suiteName: NextcloudKit.shared.nkCommonInstance.groupIdentifier) {
-
-                var unavailableArray = groupDefaults.array(forKey: "Unavailable") as? [String] ?? []
-                if !unavailableArray.contains(account) {
-                    unavailableArray.append(account)
-                    groupDefaults.set(unavailableArray, forKey: "Unavailable")
-                    groupDefaults.synchronize()
-                }
-            }
-
-            if let url = request.request?.url?.absoluteString,
-               let account = request.request?.allHTTPHeaderFields?["X-NC-Account"] as? String,
-               self.nkCommonInstance.levelLog > 0 {
-                debugPrint("[DEBUG] Monitor request url: \(url), status code \(statusCode), account: \(account)")
-            }
+        //
+        // Server Error GroupDefaults
+        //
+        if let statusCode = response.response?.statusCode,
+           let headerCheckInterceptor = request.request?.allHTTPHeaderFields?[self.nkCommonInstance.headerCheckInterceptor],
+           headerCheckInterceptor.lowercased() == "true",
+           let account = request.request?.allHTTPHeaderFields?[self.nkCommonInstance.headerAccount] as? String {
+            self.nkCommonInstance.appendServerErrorAccount(account, errorCode: statusCode)
         }
 
         //
diff --git a/Sources/NextcloudKit/NKRequestOptions.swift b/Sources/NextcloudKit/NKRequestOptions.swift
index 2c2baa68..fe5ba863 100644
--- a/Sources/NextcloudKit/NKRequestOptions.swift
+++ b/Sources/NextcloudKit/NKRequestOptions.swift
@@ -16,7 +16,7 @@ public class NKRequestOptions: NSObject {
     var taskDescription: String?
     var createProperties: [NKProperties]?
     var removeProperties: [NKProperties]
-    var checkUnauthorized: Bool?
+    var checkInterceptor: Bool
     var paginate: Bool
     var paginateToken: String?
     var paginateOffset: Int?
@@ -33,7 +33,7 @@ public class NKRequestOptions: NSObject {
                 taskDescription: String? = nil,
                 createProperties: [NKProperties]? = nil,
                 removeProperties: [NKProperties] = [],
-                checkUnauthorized: Bool? = nil,
+                checkInterceptor: Bool = true,
                 paginate: Bool = false,
                 paginateToken: String? = nil,
                 paginateOffset: Int? = nil,
@@ -50,7 +50,7 @@ public class NKRequestOptions: NSObject {
         self.taskDescription = taskDescription
         self.createProperties = createProperties
         self.removeProperties = removeProperties
-        self.checkUnauthorized = checkUnauthorized
+        self.checkInterceptor = checkInterceptor
         self.paginate = paginate
         self.paginateToken = paginateToken
         self.paginateOffset = paginateOffset
diff --git a/Sources/NextcloudKit/NextcloudKit+API.swift b/Sources/NextcloudKit/NextcloudKit+API.swift
index 42b209d0..c07077f3 100644
--- a/Sources/NextcloudKit/NextcloudKit+API.swift
+++ b/Sources/NextcloudKit/NextcloudKit+API.swift
@@ -64,13 +64,9 @@ public extension NextcloudKit {
                              options: NKRequestOptions = NKRequestOptions(),
                              taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                              completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
         let method = HTTPMethod(rawValue: method.uppercased())
@@ -100,13 +96,9 @@ public extension NextcloudKit {
                          completion: @escaping (_ account: String, _ externalFiles: [NKExternalSite], _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
         var externalSites: [NKExternalSite] = []
         let endpoint = "ocs/v2.php/apps/external/api/v1"
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, externalSites, nil, .urlError) }
         }
 
@@ -221,12 +213,8 @@ public extension NextcloudKit {
                          options: NKRequestOptions = NKRequestOptions(),
                          taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                          completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         guard let nkSession = nkCommonInstance.getSession(account: account),
-              var headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              var headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
         if var etag = etag {
@@ -264,14 +252,10 @@ public extension NextcloudKit {
                          options: NKRequestOptions = NKRequestOptions(),
                          taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                          completion: @escaping (_ account: String, _ width: Int, _ height: Int, _ etag: String?, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "index.php/core/preview?fileId=\(fileId)&x=\(width)&y=\(height)&a=\(crop)&mode=\(cropMode)&forceIcon=\(forceIcon)&mimeFallback=\(mimeFallback)"
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              var headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              var headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, width, height, nil, nil, .urlError) }
         }
 
@@ -309,15 +293,11 @@ public extension NextcloudKit {
                               options: NKRequestOptions = NKRequestOptions(),
                               taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                               completion: @escaping (_ account: String, _ width: Int, _ height: Int, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "index.php/apps/files_trashbin/preview?fileId=\(fileId)&x=\(width)&y=\(height)&a=\(crop)&mode=\(cropMode)&forceIcon=\(forceIcon)&mimeFallback=\(mimeFallback)"
 
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, width, height, nil, .urlError) }
         }
 
@@ -347,14 +327,10 @@ public extension NextcloudKit {
                         options: NKRequestOptions = NKRequestOptions(),
                         taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                         completion: @escaping (_ account: String, _ imageAvatar: UIImage?, _ imageOriginal: UIImage?, _ etag: String?, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "index.php/avatar/\(user)/\(sizeImage)"
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              var headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              var headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, nil, nil, .urlError) }
         }
 
@@ -451,13 +427,9 @@ public extension NextcloudKit {
                          options: NKRequestOptions = NKRequestOptions(),
                          taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                          completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         guard let url = serverUrl.asUrl,
               let nkSession = nkCommonInstance.getSession(account: account),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
 
@@ -484,14 +456,10 @@ public extension NextcloudKit {
                         options: NKRequestOptions = NKRequestOptions(),
                         taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                         completion: @escaping (_ account: String, _ userProfile: NKUserProfile?, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "ocs/v2.php/cloud/user"
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, .urlError) }
         }
 
@@ -557,14 +525,10 @@ public extension NextcloudKit {
                          options: NKRequestOptions = NKRequestOptions(),
                          taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                          completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "ocs/v1.php/cloud/capabilities"
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
 
@@ -672,10 +636,6 @@ public extension NextcloudKit {
                      options: NKRequestOptions = NKRequestOptions(),
                      taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                      completion: @escaping (_ account: String, _ activities: [NKActivity], _ activityFirstKnown: Int, _ activityLastGiven: Int, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         var activities: [NKActivity] = []
         var activityFirstKnown = 0
         var activityLastGiven = 0
@@ -700,7 +660,7 @@ public extension NextcloudKit {
 
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, activities, activityFirstKnown, activityLastGiven, nil, .urlError) }
         }
 
@@ -773,14 +733,10 @@ public extension NextcloudKit {
                           options: NKRequestOptions = NKRequestOptions(),
                           taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                           completion: @escaping (_ account: String, _ notifications: [NKNotifications]?, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "ocs/v2.php/apps/notifications/api/v2/notifications"
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, .urlError) }
         }
 
@@ -851,12 +807,8 @@ public extension NextcloudKit {
                          options: NKRequestOptions = NKRequestOptions(),
                          taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                          completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         guard let nkSession = nkCommonInstance.getSession(account: account),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
         var url: URLConvertible?
@@ -895,10 +847,6 @@ public extension NextcloudKit {
                            options: NKRequestOptions = NKRequestOptions(),
                            taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                            completion: @escaping (_ account: String, _ url: String?, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "ocs/v2.php/apps/dav/api/v1/direct"
         let parameters: [String: Any] = [
             "fileId": fileId,
@@ -906,7 +854,7 @@ public extension NextcloudKit {
         ]
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, .urlError) }
         }
 
@@ -937,17 +885,13 @@ public extension NextcloudKit {
                                               options: NKRequestOptions = NKRequestOptions(),
                                               taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                                               completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "ocs/v2.php/apps/security_guard/diagnostics"
         ///
         options.contentType = "application/json"
         ///
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
         var urlRequest: URLRequest
diff --git a/Sources/NextcloudKit/NextcloudKit+PushNotification.swift b/Sources/NextcloudKit/NextcloudKit+PushNotification.swift
index 18d29faa..1052157e 100644
--- a/Sources/NextcloudKit/NextcloudKit+PushNotification.swift
+++ b/Sources/NextcloudKit/NextcloudKit+PushNotification.swift
@@ -15,14 +15,10 @@ public extension NextcloudKit {
                                      options: NKRequestOptions = NKRequestOptions(),
                                      taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                                      completion: @escaping (_ account: String, _ deviceIdentifier: String?, _ signature: String?, _ publicKey: String?, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "ocs/v2.php/apps/notifications/api/v2/push"
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, nil, nil, .urlError) }
         }
         let parameters = [
@@ -62,14 +58,10 @@ public extension NextcloudKit {
                                        options: NKRequestOptions = NKRequestOptions(),
                                        taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                                        completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "ocs/v2.php/apps/notifications/api/v2/push"
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
 
diff --git a/Sources/NextcloudKit/NextcloudKit+RecommendedFiles.swift b/Sources/NextcloudKit/NextcloudKit+RecommendedFiles.swift
index 55d5e587..9bd3dea2 100644
--- a/Sources/NextcloudKit/NextcloudKit+RecommendedFiles.swift
+++ b/Sources/NextcloudKit/NextcloudKit+RecommendedFiles.swift
@@ -12,17 +12,13 @@ public extension NextcloudKit {
                              request: @escaping (DataRequest?) -> Void = { _ in },
                              taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                              completion: @escaping (_ account: String, _ recommendations: [NKRecommendation]?, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         let endpoint = "ocs/v2.php/apps/recommendations/api/v1/recommendations"
         ///
         options.contentType = "application/xml"
         ///
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = nkCommonInstance.createStandardUrl(serverUrl: nkSession.urlBase, endpoint: endpoint, options: options),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, .urlError) }
         }
 
diff --git a/Sources/NextcloudKit/NextcloudKit+WebDAV.swift b/Sources/NextcloudKit/NextcloudKit+WebDAV.swift
index 2948973a..afbe4ed6 100644
--- a/Sources/NextcloudKit/NextcloudKit+WebDAV.swift
+++ b/Sources/NextcloudKit/NextcloudKit+WebDAV.swift
@@ -12,13 +12,9 @@ public extension NextcloudKit {
                       options: NKRequestOptions = NKRequestOptions(),
                       taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                       completion: @escaping (_ account: String, _ ocId: String?, _ date: Date?, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         guard let url = serverUrlFileName.encodedToUrl,
               let nkSession = nkCommonInstance.getSession(account: account),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, nil, .urlError) }
         }
         let method = HTTPMethod(rawValue: "MKCOL")
@@ -61,13 +57,9 @@ public extension NextcloudKit {
                             options: NKRequestOptions = NKRequestOptions(),
                             taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                             completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         guard let url = serverUrlFileName.encodedToUrl,
               let nkSession = nkCommonInstance.getSession(account: account),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
         var urlRequest: URLRequest
@@ -102,13 +94,9 @@ public extension NextcloudKit {
                           options: NKRequestOptions = NKRequestOptions(),
                           taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                           completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         guard let url = serverUrlFileNameSource.encodedToUrl,
               let nkSession = nkCommonInstance.getSession(account: account),
-              var headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              var headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
         let method = HTTPMethod(rawValue: "MOVE")
@@ -150,13 +138,9 @@ public extension NextcloudKit {
                           options: NKRequestOptions = NKRequestOptions(),
                           taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                           completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         guard let url = serverUrlFileNameSource.encodedToUrl,
               let nkSession = nkCommonInstance.getSession(account: account),
-              var headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              var headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
         let method = HTTPMethod(rawValue: "COPY")
@@ -201,10 +185,6 @@ public extension NextcloudKit {
                           options: NKRequestOptions = NKRequestOptions(),
                           taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                           completion: @escaping (_ account: String, _ files: [NKFile]?, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         var files: [NKFile] = []
         var serverUrlFileName = serverUrlFileName
         ///
@@ -212,7 +192,7 @@ public extension NextcloudKit {
         ///
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let url = serverUrlFileName.encodedToUrl,
-              var headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              var headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, .urlError) }
         }
         if depth == "0", serverUrlFileName.last == "/" {
@@ -376,15 +356,11 @@ public extension NextcloudKit {
                         options: NKRequestOptions = NKRequestOptions(),
                         taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                         completion: @escaping (_ account: String, _ files: [NKFile]?, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         ///
         options.contentType = "application/xml"
         ///
         guard let nkSession = nkCommonInstance.getSession(account: account),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, .urlError) }
         }
         var files: [NKFile] = []
@@ -429,15 +405,11 @@ public extension NextcloudKit {
                      options: NKRequestOptions = NKRequestOptions(),
                      taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                      completion: @escaping (_ account: String, _ responseData: AFDataResponse<Data?>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         ///
         options.contentType = "application/xml"
         ///
         guard let nkSession = nkCommonInstance.getSession(account: account),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, .urlError) }
         }
         let serverUrlFileName = nkSession.urlBase + "/" + nkSession.dav + "/files/" + nkSession.userId + "/" + fileName
@@ -479,15 +451,11 @@ public extension NextcloudKit {
                           options: NKRequestOptions = NKRequestOptions(),
                           taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                           completion: @escaping (_ account: String, _ files: [NKFile]?, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         ///
         options.contentType = "application/xml"
         ///
         guard let nkSession = nkCommonInstance.getSession(account: account),
-              let headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              let headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, .urlError) }
         }
         let serverUrlFileName = nkSession.urlBase + "/" + nkSession.dav + "/files/" + nkSession.userId
@@ -534,15 +502,11 @@ public extension NextcloudKit {
                       options: NKRequestOptions = NKRequestOptions(),
                       taskHandler: @escaping (_ task: URLSessionTask) -> Void = { _ in },
                       completion: @escaping (_ account: String, _ items: [NKTrash]?, _ responseData: AFDataResponse<Data>?, _ error: NKError) -> Void) {
-        var checkUnauthorized = true
-        if let optionsCheckUnauthorized = options.checkUnauthorized {
-            checkUnauthorized = optionsCheckUnauthorized
-        }
         ///
         options.contentType = "application/xml"
         ///
         guard let nkSession = nkCommonInstance.getSession(account: account),
-              var headers = nkCommonInstance.getStandardHeaders(account: account, checkUnauthorized: checkUnauthorized, options: options) else {
+              var headers = nkCommonInstance.getStandardHeaders(account: account, options: options) else {
             return options.queue.async { completion(account, nil, nil, .urlError) }
         }
         var serverUrlFileName = nkSession.urlBase + "/" + nkSession.dav + "/trashbin/" + nkSession.userId + "/trash/"
diff --git a/Sources/NextcloudKit/NextcloudKitBackground.swift b/Sources/NextcloudKit/NextcloudKitBackground.swift
index 2a80b817..7a33ec87 100644
--- a/Sources/NextcloudKit/NextcloudKitBackground.swift
+++ b/Sources/NextcloudKit/NextcloudKitBackground.swift
@@ -17,32 +17,39 @@ public final class NKBackground: NSObject, URLSessionTaskDelegate, URLSessionDel
     public func download(serverUrlFileName: Any,
                          fileNameLocalPath: String,
                          taskDescription: String? = nil,
-                         account: String) -> URLSessionDownloadTask? {
+                         account: String) -> (URLSessionDownloadTask?, error: NKError) {
         var url: URL?
         let groupDefaults = UserDefaults(suiteName: NextcloudKit.shared.nkCommonInstance.groupIdentifier)
 
+        /// Check error in groupDefaults
+        if let array = groupDefaults?.array(forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsUnauthorized) as? [String],
+           array.contains(account) {
+            return (nil, .unauthorizedError)
+        } else if let array = groupDefaults?.array(forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsUnavailable) as? [String],
+                  array.contains(account) {
+            return (nil, .unavailableError)
+        } else if let array = groupDefaults?.array(forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsToS) as? [String],
+                  array.contains(account) {
+            return (nil, .forbiddenError)
+        }
+
         if serverUrlFileName is URL {
             url = serverUrlFileName as? URL
         } else if serverUrlFileName is String || serverUrlFileName is NSString {
             url = (serverUrlFileName as? String)?.encodedToUrl as? URL
         }
 
-        if let unauthorizedArray = groupDefaults?.array(forKey: "Unauthorized") as? [String],
-           unauthorizedArray.contains(account) {
-            return nil
-        }
-
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let urlForRequest = url
         else {
-            return nil
+            return (nil, .urlError)
         }
         var request = URLRequest(url: urlForRequest)
         let loginString = "\(nkSession.user):\(nkSession.password)"
 
         guard let loginData = loginString.data(using: String.Encoding.utf8)
         else {
-            return nil
+            return (nil, .invalidData)
         }
         let base64LoginString = loginData.base64EncodedString()
 
@@ -54,7 +61,7 @@ public final class NKBackground: NSObject, URLSessionTaskDelegate, URLSessionDel
         task.resume()
         self.nkCommonInstance.writeLog("Network start download file: \(serverUrlFileName)")
 
-        return task
+        return (task, .success)
     }
 
     // MARK: - Upload
@@ -66,32 +73,39 @@ public final class NKBackground: NSObject, URLSessionTaskDelegate, URLSessionDel
                        taskDescription: String? = nil,
                        overwrite: Bool = false,
                        account: String,
-                       sessionIdentifier: String) -> URLSessionUploadTask? {
+                       sessionIdentifier: String) -> (URLSessionUploadTask?, error: NKError) {
         var url: URL?
         var uploadSession: URLSession?
         let groupDefaults = UserDefaults(suiteName: NextcloudKit.shared.nkCommonInstance.groupIdentifier)
 
+        /// Check error in groupDefaults
+        if let array = groupDefaults?.array(forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsUnauthorized) as? [String],
+           array.contains(account) {
+            return (nil, .unauthorizedError)
+        } else if let array = groupDefaults?.array(forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsUnavailable) as? [String],
+                  array.contains(account) {
+            return (nil, .unavailableError)
+        } else if let array = groupDefaults?.array(forKey: NextcloudKit.shared.nkCommonInstance.groupDefaultsToS) as? [String],
+                  array.contains(account) {
+            return (nil, .forbiddenError)
+        }
+
         if serverUrlFileName is URL {
             url = serverUrlFileName as? URL
         } else if serverUrlFileName is String || serverUrlFileName is NSString {
             url = (serverUrlFileName as? String)?.encodedToUrl as? URL
         }
 
-        if let unauthorizedArray = groupDefaults?.array(forKey: "Unauthorized") as? [String],
-           unauthorizedArray.contains(account) {
-            return nil
-        }
-
         guard let nkSession = nkCommonInstance.getSession(account: account),
               let urlForRequest = url
         else {
-            return nil
+            return (nil, .urlError)
         }
 
         var request = URLRequest(url: urlForRequest)
         let loginString = "\(nkSession.user):\(nkSession.password)"
         guard let loginData = loginString.data(using: String.Encoding.utf8) else {
-            return nil
+            return (nil, .invalidData)
         }
         let base64LoginString = loginData.base64EncodedString()
 
@@ -122,7 +136,8 @@ public final class NKBackground: NSObject, URLSessionTaskDelegate, URLSessionDel
         task?.taskDescription = taskDescription
         task?.resume()
         self.nkCommonInstance.writeLog("Network start upload file: \(serverUrlFileName)")
-        return task
+
+        return (task, .success)
     }
 
     // MARK: - SessionDelegate