diff --git a/CHANGES b/CHANGES
index a73bc79f40..e3ee38e82d 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,9 @@
+6284.	[bug]		Fix a catz db update notification callback registration
+			logic error, which could cause an assertion failure when
+			receiving an AXFR update for a catalog zone while the
+			previous update process of the catalog zone was already
+			running. [GL #4418]
+
 6283.	[bug]		Fix a data race in isc_hashmap by using atomics for the
 			iterators number. [GL !8474]
 
diff --git a/lib/dns/catz.c b/lib/dns/catz.c
index 5671f3c962..809259b7bb 100644
--- a/lib/dns/catz.c
+++ b/lib/dns/catz.c
@@ -2493,15 +2493,6 @@ dns__catz_update_cb(void *data) {
 		      ISC_LOG_DEBUG(3),
 		      "catz: update_from_db: new zone merged");
 
-	/*
-	 * When we're doing reconfig and setting a new catalog zone
-	 * from an existing zone we won't have a chance to set up
-	 * update callback in zone_startload or axfr_makedb, but we will
-	 * call onupdate() artificially so we can register the callback here.
-	 */
-	dns_db_updatenotify_register(updb, dns_catz_dbupdate_callback,
-				     oldcatz->catzs);
-
 exit:
 	catz->updateresult = result;
 }