diff --git a/app/controllers/course/studygroup.php b/app/controllers/course/studygroup.php
index b75d91e0b46d84c57340ccbece97952b5b12b949..500a0b61448bef9bc5398c250dec1d3cd04ed02e 100644
--- a/app/controllers/course/studygroup.php
+++ b/app/controllers/course/studygroup.php
@@ -596,6 +596,11 @@ class Course_StudygroupController extends AuthenticatedController
         global $perm;
 
         $id = Context::getId();
+
+        if (!$id) {
+            throw new CheckObjectException(_('Sie haben kein Objekt gewählt.'));
+        }
+
         $user = Request::username('user');
 
         if ($from_status === 'moderator') {