diff --git a/src/main/java/de/hftstuttgart/unifiedticketing/systems/gitlab/GitlabTicketBuilder.java b/src/main/java/de/hftstuttgart/unifiedticketing/systems/gitlab/GitlabTicketBuilder.java
index 23a3a5d5ca01299ec44e1c7c30c4f539e50ca8b7..7b7c50d5094fb690af9fb4459ccd778f5c8003b0 100644
--- a/src/main/java/de/hftstuttgart/unifiedticketing/systems/gitlab/GitlabTicketBuilder.java
+++ b/src/main/java/de/hftstuttgart/unifiedticketing/systems/gitlab/GitlabTicketBuilder.java
@@ -37,7 +37,8 @@ public class GitlabTicketBuilder extends TicketBuilder<GitlabTicketBuilder, Gitl
         } catch (NumberFormatException e)
         {
             logger.log(Level.SEVERE, String.format("not as integer parsable assignee id encountered!"));
-            throw new AssertionException(e);
+            if (parent.getConfigTrue(TicketSystem.ConfigurationOptions.RETURN_NULL_ON_ERROR)) return this;
+            else throw new AssertionException(e);
         }
 
         return super.assignees(identifiers);