diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
index 800d58a7..657189d5 100644
--- a/.github/workflows/maven.yml
+++ b/.github/workflows/maven.yml
@@ -21,13 +21,11 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
-    - name: run tests in java 17 
-      uses: s4u/setup-maven-action@v1.14.0
+    - name: Set up JDK 17
+      uses: actions/setup-java@v4
       with:
         java-version: '17'
         distribution: 'temurin'
-        maven-version: 3.9.4
-    - name: Show maven version
-      run: mvn --version
-    - name: Build with Maven      
-      run: mvn -B package --file pom.xml
+        cache: maven
+    - name: Build with Maven
+      run: mvn -B package --file pom.xml    
\ No newline at end of file
diff --git a/cosmo-api/pom.xml b/cosmo-api/pom.xml
index 7f6404af..824b6352 100644
--- a/cosmo-api/pom.xml
+++ b/cosmo-api/pom.xml
@@ -4,7 +4,7 @@
 	<parent>
 		<groupId>net.oneandone.cosmo</groupId>
 		<artifactId>cosmo-multimodule</artifactId>
-		<version>7.0.4-SNAPSHOT</version>
+		<version>7.1.0-SNAPSHOT</version>
 	</parent>
 		
 	<artifactId>cosmo-api</artifactId>
diff --git a/cosmo-core/pom.xml b/cosmo-core/pom.xml
index b82995e7..892f44c2 100644
--- a/cosmo-core/pom.xml
+++ b/cosmo-core/pom.xml
@@ -12,7 +12,7 @@
 	<parent>
 		<groupId>net.oneandone.cosmo</groupId>
 		<artifactId>cosmo-multimodule</artifactId>
-		<version>7.0.4-SNAPSHOT</version>
+		<version>7.1.0-SNAPSHOT</version>
 	</parent>
 	<modelVersion>4.0.0</modelVersion>
 	<artifactId>cosmo-core</artifactId>	
diff --git a/cosmo-core/src/main/java/org/unitedinternet/cosmo/dao/hibernate/ContentDaoImpl.java b/cosmo-core/src/main/java/org/unitedinternet/cosmo/dao/hibernate/ContentDaoImpl.java
index 3df81db4..6d9db511 100644
--- a/cosmo-core/src/main/java/org/unitedinternet/cosmo/dao/hibernate/ContentDaoImpl.java
+++ b/cosmo-core/src/main/java/org/unitedinternet/cosmo/dao/hibernate/ContentDaoImpl.java
@@ -28,6 +28,7 @@
 import org.unitedinternet.cosmo.dao.ContentDao;
 import org.unitedinternet.cosmo.dao.ModelValidationException;
 import org.unitedinternet.cosmo.model.CollectionItem;
+import org.unitedinternet.cosmo.model.CollectionSubscription;
 import org.unitedinternet.cosmo.model.ContentItem;
 import org.unitedinternet.cosmo.model.ICalendarItem;
 import org.unitedinternet.cosmo.model.IcalUidInUseException;
@@ -35,6 +36,7 @@
 import org.unitedinternet.cosmo.model.NoteItem;
 import org.unitedinternet.cosmo.model.User;
 import org.unitedinternet.cosmo.model.hibernate.HibCollectionItem;
+import org.unitedinternet.cosmo.model.hibernate.HibCollectionSubscriptionItem;
 import org.unitedinternet.cosmo.model.hibernate.HibItem;
 import org.unitedinternet.cosmo.model.hibernate.HibItemTombstone;
 
@@ -346,6 +348,13 @@ private void removeCollectionRecursive(CollectionItem collection) {
          * Removing a collection does not automatically remove its children. Instead, the association to all the
          * children is removed, and any children who have no parent collection are then removed.
          */
+        if (collection instanceof HibCollectionSubscriptionItem) {
+            HibCollectionSubscriptionItem subCollection = (HibCollectionSubscriptionItem) collection;
+            CollectionSubscription subScription = subCollection.getSubscription();
+            if (subScription != null) {
+                this.em.detach(subScription);
+            }
+        }
         removeItemsFromCollection(collection);
         this.em.remove(collection);
     }
diff --git a/pom.xml b/pom.xml
index 6c08c1b7..ef281aeb 100644
--- a/pom.xml
+++ b/pom.xml
@@ -12,7 +12,7 @@
 
 	<groupId>net.oneandone.cosmo</groupId>
 	<artifactId>cosmo-multimodule</artifactId>
-	<version>7.0.4-SNAPSHOT</version>
+	<version>7.1.0-SNAPSHOT</version>
 	<packaging>pom</packaging>
 	<name>cosmo-multimodule</name>
 	<description>CalDAV core implementation server</description>
@@ -27,7 +27,7 @@
 		<qxlint.report.profile>false</qxlint.report.profile>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		
-		<spring.boot.version>3.3.1</spring.boot.version>		
+		<spring.boot.version>3.4.4</spring.boot.version>		
 						
 		<jackrabbit.version>3.0.1</jackrabbit.version>
 		<ical4j.version>3.2.14</ical4j.version>
@@ -40,7 +40,7 @@
 		<stax.version>1.0.1</stax.version>
 		<woodstox.version>4.0.6</woodstox.version>
 		
-		<jackson.version>2.17.2</jackson.version>
+		<jackson.version>2.18.3</jackson.version>
 		<abdera.version>1.1.3</abdera.version>
 		<junit.version>5.10.3</junit.version>