diff --git a/lib-ee/emqx_license/src/emqx_license.erl b/lib-ee/emqx_license/src/emqx_license.erl
index 412a1a1d3..d7a9fc252 100644
--- a/lib-ee/emqx_license/src/emqx_license.erl
+++ b/lib-ee/emqx_license/src/emqx_license.erl
@@ -94,6 +94,7 @@ check(_ConnInfo, AckProps) ->
 pre_config_update(_, Cmd, Conf) ->
     {ok, do_update(Cmd, Conf)}.
 
+post_config_update(_Path, _Cmd, ignore, _Old, _AppEnvs) -> ok;
 post_config_update(_Path, _Cmd, NewConf, _Old, _AppEnvs) ->
     case read_license(NewConf) of
         {ok, License} ->
@@ -131,7 +132,10 @@ do_update({key, Content}, _Conf) when is_binary(Content); is_list(Content) ->
             #{<<"key">> => Content};
         {error, Reason} ->
             erlang:throw(Reason)
-    end.
+    end;
+%% We don't do extra action when update license's watermark.
+do_update(_Other, _Conf) ->
+    {ok, ignore}.
 
 check_max_clients_exceeded(MaxClients) ->
     emqx_license_resources:connection_count() > MaxClients * 1.1.