diff --git a/apps/emqx/src/emqx_config.erl b/apps/emqx/src/emqx_config.erl
index 3d602349d..9bf098ec4 100644
--- a/apps/emqx/src/emqx_config.erl
+++ b/apps/emqx/src/emqx_config.erl
@@ -414,9 +414,8 @@ check_config(SchemaMod, RawConf) ->
 check_config(SchemaMod, RawConf, Opts0) ->
     Opts1 = #{
         return_plain => true,
-        %% TODO: evil, remove, required should be declared in schema
-        required => false,
-        format => map
+        format => map,
+        check_lazy => true
     },
     Opts = maps:merge(Opts0, Opts1),
     {AppEnvs, CheckedConf} =
diff --git a/apps/emqx/src/emqx_schema.erl b/apps/emqx/src/emqx_schema.erl
index 35550d4e2..0bc028ec8 100644
--- a/apps/emqx/src/emqx_schema.erl
+++ b/apps/emqx/src/emqx_schema.erl
@@ -2245,6 +2245,7 @@ validate_alarm_actions(Actions) ->
         Error -> {error, Error}
     end.
 
+parse_user_lookup_fun({Fun, _} = Lookup) when is_function(Fun, 3) -> Lookup;
 parse_user_lookup_fun(StrConf) ->
     [ModStr, FunStr] = string:tokens(str(StrConf), ": "),
     Mod = list_to_atom(ModStr),