diff --git a/hawkbit-repository/hawkbit-repository-api/src/main/java/org/eclipse/hawkbit/repository/TargetManagement.java b/hawkbit-repository/hawkbit-repository-api/src/main/java/org/eclipse/hawkbit/repository/TargetManagement.java
index 58be29bca5..7194fab9e5 100644
--- a/hawkbit-repository/hawkbit-repository-api/src/main/java/org/eclipse/hawkbit/repository/TargetManagement.java
+++ b/hawkbit-repository/hawkbit-repository-api/src/main/java/org/eclipse/hawkbit/repository/TargetManagement.java
@@ -125,6 +125,20 @@ long countByFilters(Collection<TargetUpdateStatus> status, Boolean overdueState,
             + SpringEvalExpressions.HAS_AUTH_READ_REPOSITORY)
     long countByInstalledDistributionSet(long distId);
 
+    /**
+     * Checks if there is already a {@link Target} that has the given distribution set Id assigned or installed.
+     *
+     * @param distId
+     *            to search for
+     * @return <code>true</code> if a {@link Target} exists.
+     *
+     * @throws EntityNotFoundException
+     *             if distribution set with given ID does not exist
+     */
+    @PreAuthorize(SpringEvalExpressions.HAS_AUTH_READ_TARGET + SpringEvalExpressions.HAS_AUTH_OR
+                          + SpringEvalExpressions.HAS_AUTH_READ_REPOSITORY)
+    boolean existsByInstalledOrAssignedDistributionSet(long distId);
+
     /**
      * Count {@link TargetFilterQuery}s for given target filter query.
      *
diff --git a/hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/JpaTargetManagement.java b/hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/JpaTargetManagement.java
index 8e14504801..e2549c32f9 100644
--- a/hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/JpaTargetManagement.java
+++ b/hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/JpaTargetManagement.java
@@ -646,6 +646,13 @@ public long countByInstalledDistributionSet(final long distId) {
         return targetRepository.countByInstalledDistributionSetId(distId);
     }
 
+    @Override
+    public boolean existsByInstalledOrAssignedDistributionSet(final long distId) {
+        throwEntityNotFoundIfDsDoesNotExist(distId);
+
+        return targetRepository.existsByInstalledOrAssignedDistributionSet(distId);
+    }
+
     @Override
     public Page<Target> findByTargetFilterQueryAndNonDS(final Pageable pageRequest, final long distributionSetId,
             final String targetFilterQuery) {
diff --git a/hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/TargetRepository.java b/hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/TargetRepository.java
index 59146744e6..474920f761 100644
--- a/hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/TargetRepository.java
+++ b/hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/TargetRepository.java
@@ -208,6 +208,16 @@ List<JpaTarget> findByTagNameAndControllerIdIn(@Param("tagname") String tag,
      */
     Long countByInstalledDistributionSetId(Long distId);
 
+    /**
+     * Checks if there is already a {@link Target} that has the given distribution set Id assigned or installed.
+     *
+     * @param distId
+     *            to check
+     * @return <code>true</code> if a {@link Target} exists.
+     */
+    @Query("SELECT CASE WHEN COUNT(t)>0 THEN 'true' ELSE 'false' END FROM JpaTarget t WHERE t.installedDistributionSet.id=:distId OR t.assignedDistributionSet.id=:distId")
+    boolean existsByInstalledOrAssignedDistributionSet(@Param("distId") Long distId);
+
     /**
      * Finds all {@link Target}s in the repository.
      *
diff --git a/hawkbit-repository/hawkbit-repository-jpa/src/test/java/org/eclipse/hawkbit/repository/jpa/TargetManagementTest.java b/hawkbit-repository/hawkbit-repository-jpa/src/test/java/org/eclipse/hawkbit/repository/jpa/TargetManagementTest.java
index 3bb78a5385..992af5e1d2 100644
--- a/hawkbit-repository/hawkbit-repository-jpa/src/test/java/org/eclipse/hawkbit/repository/jpa/TargetManagementTest.java
+++ b/hawkbit-repository/hawkbit-repository-jpa/src/test/java/org/eclipse/hawkbit/repository/jpa/TargetManagementTest.java
@@ -39,9 +39,9 @@
 import org.eclipse.hawkbit.repository.event.remote.entity.TargetCreatedEvent;
 import org.eclipse.hawkbit.repository.event.remote.entity.TargetTagCreatedEvent;
 import org.eclipse.hawkbit.repository.event.remote.entity.TargetUpdatedEvent;
+import org.eclipse.hawkbit.repository.exception.AssignmentQuotaExceededException;
 import org.eclipse.hawkbit.repository.exception.EntityAlreadyExistsException;
 import org.eclipse.hawkbit.repository.exception.InvalidTargetAddressException;
-import org.eclipse.hawkbit.repository.exception.AssignmentQuotaExceededException;
 import org.eclipse.hawkbit.repository.exception.TenantNotExistException;
 import org.eclipse.hawkbit.repository.jpa.model.JpaTarget;
 import org.eclipse.hawkbit.repository.jpa.model.JpaTargetMetadata;
@@ -108,6 +108,8 @@ public void entityQueriesReferringToNotExistingEntitiesThrowsException() {
                 "DistributionSet");
         verifyThrownExceptionBy(() -> targetManagement.countByInstalledDistributionSet(NOT_EXIST_IDL),
                 "DistributionSet");
+        verifyThrownExceptionBy(() -> targetManagement.existsByInstalledOrAssignedDistributionSet(NOT_EXIST_IDL),
+                "DistributionSet");
 
         verifyThrownExceptionBy(() -> targetManagement.countByTargetFilterQuery(NOT_EXIST_IDL), "TargetFilterQuery");
         verifyThrownExceptionBy(() -> targetManagement.countByRsqlAndNonDS(NOT_EXIST_IDL, "name==*"),
@@ -465,10 +467,14 @@ public void findTargetByControllerIDWithDetails() {
                 .isEqualTo(0);
         assertThat(targetManagement.countByInstalledDistributionSet(set.getId())).as("Target count is wrong")
                 .isEqualTo(0);
+        assertThat(targetManagement.existsByInstalledOrAssignedDistributionSet(set.getId())).as("Target count is wrong")
+                .isFalse();
         assertThat(targetManagement.countByAssignedDistributionSet(set2.getId())).as("Target count is wrong")
                 .isEqualTo(0);
         assertThat(targetManagement.countByInstalledDistributionSet(set2.getId())).as("Target count is wrong")
                 .isEqualTo(0);
+        assertThat(targetManagement.existsByInstalledOrAssignedDistributionSet(set2.getId())).as("Target count is wrong")
+                .isFalse();
 
         Target target = createTargetWithAttributes("4711");
 
@@ -488,10 +494,14 @@ public void findTargetByControllerIDWithDetails() {
                 .isEqualTo(0);
         assertThat(targetManagement.countByInstalledDistributionSet(set.getId())).as("Target count is wrong")
                 .isEqualTo(1);
+        assertThat(targetManagement.existsByInstalledOrAssignedDistributionSet(set.getId())).as("Target count is wrong")
+                .isTrue();
         assertThat(targetManagement.countByAssignedDistributionSet(set2.getId())).as("Target count is wrong")
                 .isEqualTo(1);
         assertThat(targetManagement.countByInstalledDistributionSet(set2.getId())).as("Target count is wrong")
                 .isEqualTo(0);
+        assertThat(targetManagement.existsByInstalledOrAssignedDistributionSet(set2.getId())).as("Target count is wrong")
+                .isTrue();
         assertThat(target.getLastTargetQuery()).as("Target query is not work").isGreaterThanOrEqualTo(current);
         assertThat(deploymentManagement.getAssignedDistributionSet("4711").get()).as("Assigned ds size is wrong")
                 .isEqualTo(set2);
diff --git a/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/grid/support/assignment/SwModulesToDistributionSetAssignmentSupport.java b/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/grid/support/assignment/SwModulesToDistributionSetAssignmentSupport.java
index b717c01e6b..cb3d458ace 100644
--- a/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/grid/support/assignment/SwModulesToDistributionSetAssignmentSupport.java
+++ b/hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/grid/support/assignment/SwModulesToDistributionSetAssignmentSupport.java
@@ -114,8 +114,8 @@ private boolean isTargetDsValid(final ProxyDistributionSet ds, final Distributio
             return false;
         }
 
-        if (targetManagement.countByFilters(null, null, null, ds.getId(), Boolean.FALSE, "") > 0) {
-            /* Distribution is already assigned */
+        if (targetManagement.existsByInstalledOrAssignedDistributionSet(ds.getId())) {
+            /* Distribution is already assigned/installed */
             notification.displayValidationError(i18n.getMessage("message.dist.inuse", ds.getNameVersion()));
             return false;
         }