diff --git a/apps/emqx/src/emqx_config.erl b/apps/emqx/src/emqx_config.erl
index 450f3e1b0..2f2c711ef 100644
--- a/apps/emqx/src/emqx_config.erl
+++ b/apps/emqx/src/emqx_config.erl
@@ -325,22 +325,32 @@ init_load(SchemaMod, Conf) when is_list(Conf) orelse is_binary(Conf) ->
     ok = save_schema_mod_and_names(SchemaMod),
     HasDeprecatedFile = has_deprecated_file(),
     RawConf0 = load_config_files(HasDeprecatedFile, Conf),
-    warning_deprecated_root_key(RawConf0),
-    RawConf1 =
+    RawConf1 = upgrade_raw_conf(SchemaMod, RawConf0),
+    warning_deprecated_root_key(RawConf1),
+    RawConf2 =
         case HasDeprecatedFile of
             true ->
-                overlay_v0(SchemaMod, RawConf0);
+                overlay_v0(SchemaMod, RawConf1);
             false ->
-                overlay_v1(SchemaMod, RawConf0)
+                overlay_v1(SchemaMod, RawConf1)
         end,
-    RawConf = fill_defaults_for_all_roots(SchemaMod, RawConf1),
+    RawConf3 = fill_defaults_for_all_roots(SchemaMod, RawConf2),
     %% check configs against the schema
-    {AppEnvs, CheckedConf} = check_config(SchemaMod, RawConf, #{}),
+    {AppEnvs, CheckedConf} = check_config(SchemaMod, RawConf3, #{}),
     save_to_app_env(AppEnvs),
-    ok = save_to_config_map(CheckedConf, RawConf),
+    ok = save_to_config_map(CheckedConf, RawConf3),
     maybe_init_default_zone(),
     ok.
 
+upgrade_raw_conf(SchemaMod, RawConf) ->
+    case erlang:function_exported(SchemaMod, upgrade_raw_conf, 1) of
+        true ->
+            %% TODO make it a schema module behaviour in hocon_schema
+            apply(SchemaMod, upgrade_raw_conf, [RawConf]);
+        false ->
+            RawConf
+    end.
+
 %% Merge environment variable overrides on top, then merge with overrides.
 overlay_v0(SchemaMod, RawConf) when is_map(RawConf) ->
     RawConfWithEnvs = merge_envs(SchemaMod, RawConf),
diff --git a/apps/emqx/src/emqx_config_handler.erl b/apps/emqx/src/emqx_config_handler.erl
index f38c5563a..bf11c17e8 100644
--- a/apps/emqx/src/emqx_config_handler.erl
+++ b/apps/emqx/src/emqx_config_handler.erl
@@ -19,7 +19,7 @@
 
 -include("logger.hrl").
 -include("emqx_schema.hrl").
--include_lib("hocon/include/hoconsc.hrl").
+-include_lib("hocon/include/hocon_types.hrl").
 
 -behaviour(gen_server).
 
@@ -736,7 +736,7 @@ remove_empty_leaf(KeyPath, Handlers) ->
     end.
 
 assert_callback_function(Mod) ->
-    _ = Mod:module_info(),
+    _ = apply(Mod, module_info, []),
     case
         erlang:function_exported(Mod, pre_config_update, 3) orelse
             erlang:function_exported(Mod, post_config_update, 5)