diff --git a/osm_nbi/k8s_topics.py b/osm_nbi/k8s_topics.py
index c9304725504dc88c63bf8fad917c26b10149731e..6e7fd256f5801ffb456e5e1cc35c830508cabce0 100644
--- a/osm_nbi/k8s_topics.py
+++ b/osm_nbi/k8s_topics.py
@@ -565,7 +565,7 @@ class ClusterTopic(ACMTopic):
         check = self.db.get_one(self.topic, filter_q)
         if check["created"] == "false":
             raise EngineException(
-                "Cannot delete registered cluster",
+                "Cannot delete registered cluster. Please deregister.",
                 HTTPStatus.UNPROCESSABLE_ENTITY,
             )
         super().delete(session, _id, dry_run=False, not_send_msg=None)