diff --git a/src/main/java/org/olat/modules/fo/ui/MessageListController.java b/src/main/java/org/olat/modules/fo/ui/MessageListController.java
index 2cfddeb97745336b85a84bd51d2f972af91b5595..9635e714dd1bfef6726b1a0064d33769bd4f5295 100644
--- a/src/main/java/org/olat/modules/fo/ui/MessageListController.java
+++ b/src/main/java/org/olat/modules/fo/ui/MessageListController.java
@@ -871,6 +871,10 @@ public class MessageListController extends BasicController implements GenericEve
 		if (foCallback.mayReplyMessage()) {
 			Message newMessage = forumManager.createMessage(forum, getIdentity(), guestOnly);
 			Message parentMessage = forumManager.getMessageById(parent.getKey());
+			if(parentMessage == null) {
+				handleEditError(ureq);
+				return;
+			}
 			
 			String reString = "";
 			if(parent != null && parent.isThreadTop()) {