diff --git a/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/detailslayout/SoftwareModuleDetailsTable.java b/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/detailslayout/SoftwareModuleDetailsTable.java
index 1af6aabe1..a7adb8711 100644
--- a/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/detailslayout/SoftwareModuleDetailsTable.java
+++ b/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/detailslayout/SoftwareModuleDetailsTable.java
@@ -186,12 +186,17 @@ public class SoftwareModuleDetailsTable extends Table {
     private void unassignSW(final ClickEvent event, final DistributionSet distributionSet,
             final Set<SoftwareModule> alreadyAssignedSwModules) {
         final SoftwareModule unAssignedSw = getSoftwareModule(event.getButton().getId(), alreadyAssignedSwModules);
-        final DistributionSet newDistributionSet = distributionSetManagement.unassignSoftwareModule(distributionSet,
-                unAssignedSw);
-        manageDistUIState.setLastSelectedEntity(DistributionSetIdName.generate(newDistributionSet));
-        eventBus.publish(this, new DistributionTableEvent(BaseEntityEventType.SELECTED_ENTITY, newDistributionSet));
-        eventBus.publish(this, DistributionsUIEvent.ORDER_BY_DISTRIBUTION);
-        uiNotification.displaySuccess(i18n.get("message.sw.unassigned", unAssignedSw.getName()));
+        if (distributionSetManagement.isDistributionSetInUse(distributionSet)) {
+            uiNotification.displayValidationError(i18n.get("message.error.notification.ds.target.assigned",distributionSet.getName(), distributionSet.getVersion()));
+        } else {
+            final DistributionSet newDistributionSet = distributionSetManagement.unassignSoftwareModule(distributionSet,
+                    unAssignedSw);
+            manageDistUIState.setLastSelectedEntity(DistributionSetIdName.generate(newDistributionSet));
+            eventBus.publish(this, new DistributionTableEvent(BaseEntityEventType.SELECTED_ENTITY, newDistributionSet));
+            eventBus.publish(this, DistributionsUIEvent.ORDER_BY_DISTRIBUTION);
+            uiNotification.displaySuccess(i18n.get("message.sw.unassigned", unAssignedSw.getName()));
+        }
+
     }
 
     private static boolean isSoftModAvaiableForSoftType(final Set<SoftwareModule> swModulesSet,
diff --git a/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/distributions/dstable/DistributionSetTable.java b/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/distributions/dstable/DistributionSetTable.java
index 1547ef11b..fc415f4de 100644
--- a/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/distributions/dstable/DistributionSetTable.java
+++ b/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/distributions/dstable/DistributionSetTable.java
@@ -334,9 +334,7 @@ public class DistributionSetTable extends AbstractNamedVersionTable<Distribution
         }
 
         if (distributionSetManagement.isDistributionSetInUse(ds)) {
-            notification.displayValidationError(
-                    String.format("Distribution set %s:%s is already assigned to targets and cannot be changed",
-                            ds.getName(), ds.getVersion()));
+            notification.displayValidationError(i18n.get("message.error.notification.ds.target.assigned", ds.getName(), ds.getVersion()));
             return false;
         }
         return true;
@@ -506,7 +504,7 @@ public class DistributionSetTable extends AbstractNamedVersionTable<Distribution
         return columnList;
     }
 
-    private Button createManageMetadataButton(String nameVersionStr) {
+    private Button createManageMetadataButton(final String nameVersionStr) {
         final Button manageMetadataBtn = SPUIComponentProvider.getButton(
                 SPUIComponentIdProvider.DS_TABLE_MANAGE_METADATA_ID + "." + nameVersionStr, "", "", null, false,
                 FontAwesome.LIST_ALT, SPUIButtonStyleSmallNoBorder.class);
@@ -515,8 +513,8 @@ public class DistributionSetTable extends AbstractNamedVersionTable<Distribution
         return manageMetadataBtn;
     }
 
-    private void showMetadataDetails(Long itemId) {
-        DistributionSet ds = distributionSetManagement.findDistributionSetByIdWithDetails(itemId);
+    private void showMetadataDetails(final Long itemId) {
+        final DistributionSet ds = distributionSetManagement.findDistributionSetByIdWithDetails(itemId);
         UI.getCurrent().addWindow(dsMetadataPopupLayout.getWindow(ds,null));
     }
 
diff --git a/hawkbit-ui/src/main/resources/messages.properties b/hawkbit-ui/src/main/resources/messages.properties
index 383341f4f..bb399ddf1 100644
--- a/hawkbit-ui/src/main/resources/messages.properties
+++ b/hawkbit-ui/src/main/resources/messages.properties
@@ -386,6 +386,7 @@ message.metadata.updated = Metadata with key {0} successfully updated !
 message.metadata.duplicate.check = Metadata with key {0} already exists, please enter another value
 message.metadata.deleted.successfully = Metadata with key {0} successfully deleted !
 message.confirm.delete.metadata = Are you sure that you want to delete metadata with key {0} ?
+message.error.notification.ds.target.assigned = Distribution set {0}:{1} is already assigned to targets and cannot be changed
 
 # Login view
 notification.login.title=Welcome to Bosch IoT Software Provisioning.
diff --git a/hawkbit-ui/src/main/resources/messages_de.properties b/hawkbit-ui/src/main/resources/messages_de.properties
index cec24e1d8..fa62091fd 100644
--- a/hawkbit-ui/src/main/resources/messages_de.properties
+++ b/hawkbit-ui/src/main/resources/messages_de.properties
@@ -375,6 +375,7 @@ message.metadata.updated = Metadata with key {0} successfully updated !
 message.metadata.duplicate.check = Metadata with key {0} already exists, please enter another value
 message.metadata.deleted.successfully = Metadata with key {0} successfully deleted !
 message.confirm.delete.metadata = Are you sure that you want to delete metadata with key {0} ?
+message.error.notification.ds.target.assigned = Distribution set {0}:{1} is already assigned to targets and cannot be changed
 
 
 # Login view
diff --git a/hawkbit-ui/src/main/resources/messages_en.properties b/hawkbit-ui/src/main/resources/messages_en.properties
index dbb2b5c6f..65e63c228 100644
--- a/hawkbit-ui/src/main/resources/messages_en.properties
+++ b/hawkbit-ui/src/main/resources/messages_en.properties
@@ -371,6 +371,7 @@ message.metadata.updated = Metadata with key {0} successfully updated !
 message.metadata.duplicate.check = Metadata with key {0} already exists, please enter another value
 message.metadata.deleted.successfully = Metadata with key {0} successfully deleted !
 message.confirm.delete.metadata = Are you sure that you want to delete metadata with key {0} ?
+message.error.notification.ds.target.assigned = Distribution set {0}:{1} is already assigned to targets and cannot be changed
 
 # Login view
 notification.login.title=Welcome to Bosch IoT Software Provisioning.