diff --git a/EMS/core-bundle/src/Exception/DuplicateOuuidException.php b/EMS/core-bundle/src/Exception/DuplicateOuuidException.php
index 5e6eaeddb..319b4f51f 100644
--- a/EMS/core-bundle/src/Exception/DuplicateOuuidException.php
+++ b/EMS/core-bundle/src/Exception/DuplicateOuuidException.php
@@ -1,7 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace EMS\CoreBundle\Exception;
 
 class DuplicateOuuidException extends ElasticmsException
 {
+    public function __construct(string $ouuid, string $contentTypeName)
+    {
+        parent::__construct(
+            message: \sprintf('Duplicate ouuid "%s" for content type "%s"', $ouuid, $contentTypeName)
+        );
+    }
 }
diff --git a/EMS/core-bundle/src/Service/DataService.php b/EMS/core-bundle/src/Service/DataService.php
index cd57d7424..cd1086dd0 100644
--- a/EMS/core-bundle/src/Service/DataService.php
+++ b/EMS/core-bundle/src/Service/DataService.php
@@ -49,7 +49,6 @@
 use Symfony\Component\Form\FormInterface;
 use Symfony\Component\Form\FormRegistryInterface;
 use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
-use Symfony\Component\HttpKernel\Exception\ConflictHttpException;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;
 use Symfony\Component\Security\Core\Authorization\AuthorizationCheckerInterface;
@@ -443,32 +442,18 @@ public function createData(?string $ouuid, array $rawdata, ContentType $contentT
         $newRevision->setEndTime(null);
         $newRevision->setDeleted(false);
         $newRevision->setDraft(true);
-        if ($byARealUser) {
-            $token = $this->tokenStorage->getToken();
-            if (null === $token) {
-                throw new \RuntimeException('Unexpected null token');
-            }
-            $newRevision->setLockBy($token->getUserIdentifier());
-        } else {
-            $newRevision->setLockBy('DATA_SERVICE');
-        }
+
+        $lockBy = $byARealUser ? $this->userService->getCurrentUser()->getUserIdentifier() : 'DATA_SERVICE';
+        $newRevision->setLockBy($lockBy);
+
         $newRevision->setLockUntil($until);
         $newRevision->setRawData($rawdata);
 
-        $em = $this->doctrine->getManager();
-        if (!empty($ouuid)) {
-            $revisionRepository = $em->getRepository(Revision::class);
-            $anotherObject = $revisionRepository->findOneBy([
-                    'contentType' => $contentType,
-                    'ouuid' => $newRevision->getOuuid(),
-                    'endTime' => null,
-            ]);
-
-            if (!empty($anotherObject)) {
-                throw new ConflictHttpException('Duplicate OUUID '.$ouuid.' for this content type');
-            }
+        if (null !== $ouuid && null !== $this->revRepository->getCurrentRevision($contentType, $ouuid)) {
+            throw new DuplicateOuuidException($ouuid, $contentType->getName());
         }
 
+        $em = $this->doctrine->getManager();
         $em->persist($newRevision);
         $em->flush();
 
@@ -939,8 +924,8 @@ public function newDocument(ContentType $contentType, ?string $ouuid = null, ?ar
 
         $revision = new Revision();
 
-        if (null !== $ouuid && $revisionRepository->countRevisions($ouuid, $contentType)) {
-            throw new DuplicateOuuidException();
+        if (null !== $ouuid && $revisionRepository->getCurrentRevision($contentType, $ouuid)) {
+            throw new DuplicateOuuidException($ouuid, $contentType->getName());
         }
 
         if (!empty($contentType->getDefaultValue())) {