--- a/hgext3rd/topic/destination.py	Thu Apr 18 12:39:41 2019 +0200
+++ b/hgext3rd/topic/destination.py	Thu Apr 18 12:40:53 2019 +0200
@@ -62,6 +62,8 @@
 
 def _destupdatetopic(repo, clean, check=None):
     """decide on an update destination from current topic"""
+    if not common.hastopicext(repo):
+        return None, None, None
     movemark = node = None
     topic = repo.currenttopic
     if topic: