diff --git a/apps/emqx/src/emqx_map_lib.erl b/apps/emqx/src/emqx_map_lib.erl
index 52a96fea7..7eef2cd29 100644
--- a/apps/emqx/src/emqx_map_lib.erl
+++ b/apps/emqx/src/emqx_map_lib.erl
@@ -30,7 +30,8 @@
     binary_string/1,
     deep_convert/3,
     diff_maps/2,
-    merge_with/3
+    merge_with/3,
+    best_effort_recursive_sum/3
 ]).
 
 -export_type([config_key/0, config_key_path/0]).
@@ -242,10 +243,8 @@ merge_with(Combiner, Map1, Map2) when
             )
     end;
 merge_with(Combiner, Map1, Map2) ->
-    error_with_info(
-        error_type_merge_intersect(Map1, Map2, Combiner),
-        [Combiner, Map1, Map2]
-    ).
+    ErrorType = error_type_merge_intersect(Map1, Map2, Combiner),
+    throw(#{maps_merge_error => ErrorType, args => [Map1, Map2]}).
 
 merge_with_t({K, V2, Iterator}, Map1, Map2, Combiner) ->
     case Map1 of
@@ -261,12 +260,26 @@ merge_with_t(none, Result, _, _) ->
 error_type_merge_intersect(M1, M2, Combiner) when is_function(Combiner, 3) ->
     error_type_two_maps(M1, M2);
 error_type_merge_intersect(_M1, _M2, _Combiner) ->
-    badarg.
-
-error_with_info(_, _) ->
-    {error_info, #{module => erl_stdlib_errors}}.
+    badarg_combiner_function.
 
 error_type_two_maps(M1, M2) when is_map(M1) ->
     {badmap, M2};
 error_type_two_maps(M1, _M2) ->
     {badmap, M1}.
+
+%% @doc Sum-merge map values.
+%% For bad merges, ErrorLogger is called to log the key, and value in M2 is ignored.
+best_effort_recursive_sum(M1, M2, ErrorLogger) ->
+    F =
+        fun(Key, V1, V2) ->
+            case {erlang:is_map(V1), erlang:is_map(V2)} of
+                {true, true} ->
+                    best_effort_recursive_sum(V1, V2, ErrorLogger);
+                {false, false} when is_number(V1) andalso is_number(V2) ->
+                    V1 + V2;
+                _ ->
+                    ErrorLogger(#{failed_to_merge => Key}),
+                    V1
+            end
+        end,
+    merge_with(F, M1, M2).
diff --git a/apps/emqx/test/emqx_map_lib_tests.erl b/apps/emqx/test/emqx_map_lib_tests.erl
new file mode 100644
index 000000000..2a5a50cc3
--- /dev/null
+++ b/apps/emqx/test/emqx_map_lib_tests.erl
@@ -0,0 +1,56 @@
+%%--------------------------------------------------------------------
+%% Copyright (c) 2022 EMQ Technologies Co., Ltd. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%--------------------------------------------------------------------
+
+-module(emqx_map_lib_tests).
+-include_lib("eunit/include/eunit.hrl").
+
+best_effort_recursive_sum_test_() ->
+    DummyLogger = fun(_) -> ok end,
+    [
+        ?_assertEqual(
+            #{foo => 3},
+            emqx_map_lib:best_effort_recursive_sum(#{foo => 1}, #{foo => 2}, DummyLogger)
+        ),
+        ?_assertEqual(
+            #{foo => 3, bar => 6.0},
+            emqx_map_lib:best_effort_recursive_sum(
+                #{foo => 1, bar => 2.0}, #{foo => 2, bar => 4.0}, DummyLogger
+            )
+        ),
+        ?_assertEqual(
+            #{foo => 1, bar => 2},
+            emqx_map_lib:best_effort_recursive_sum(#{foo => 1}, #{bar => 2}, DummyLogger)
+        ),
+        ?_assertEqual(
+            #{foo => #{bar => 42}},
+            emqx_map_lib:best_effort_recursive_sum(
+                #{foo => #{bar => 2}}, #{foo => #{bar => 40}}, DummyLogger
+            )
+        ),
+        fun() ->
+            Self = self(),
+            Logger = fun(What) -> Self ! {log, What} end,
+            ?assertEqual(
+                #{foo => 1, bar => 2},
+                emqx_map_lib:best_effort_recursive_sum(#{foo => 1, bar => 2}, #{bar => bar}, Logger)
+            ),
+            receive
+                {log, Log} ->
+                    ?assertEqual(#{failed_to_merge => bar}, Log)
+            after 1000 -> error(timeout)
+            end
+        end
+    ].
diff --git a/apps/emqx_authn/src/emqx_authn_api.erl b/apps/emqx_authn/src/emqx_authn_api.erl
index 834ea8f7d..fa79e0d0f 100644
--- a/apps/emqx_authn/src/emqx_authn_api.erl
+++ b/apps/emqx_authn/src/emqx_authn_api.erl
@@ -1006,15 +1006,9 @@ aggregate_status(AllStatus) ->
 aggregate_metrics([]) ->
     #{};
 aggregate_metrics([HeadMetrics | AllMetrics]) ->
-    CombinerFun =
-        fun ComFun(_Key, Val1, Val2) ->
-            case erlang:is_map(Val1) of
-                true -> emqx_map_lib:merge_with(ComFun, Val1, Val2);
-                false -> Val1 + Val2
-            end
-        end,
+    ErrorLogger = fun(Reason) -> ?SLOG(info, #{msg => "bad_metrics_value", error => Reason}) end,
     Fun = fun(ElemMap, AccMap) ->
-        emqx_map_lib:merge_with(CombinerFun, ElemMap, AccMap)
+        emqx_map_lib:best_effort_recursive_sum(AccMap, ElemMap, ErrorLogger)
     end,
     lists:foldl(Fun, HeadMetrics, AllMetrics).
 
diff --git a/apps/emqx_authz/src/emqx_authz_api_sources.erl b/apps/emqx_authz/src/emqx_authz_api_sources.erl
index f4696c0a6..2dfc6da33 100644
--- a/apps/emqx_authz/src/emqx_authz_api_sources.erl
+++ b/apps/emqx_authz/src/emqx_authz_api_sources.erl
@@ -369,15 +369,9 @@ aggregate_status(AllStatus) ->
 aggregate_metrics([]) ->
     #{};
 aggregate_metrics([HeadMetrics | AllMetrics]) ->
-    CombinerFun =
-        fun ComFun(_Key, Val1, Val2) ->
-            case erlang:is_map(Val1) of
-                true -> emqx_map_lib:merge_with(ComFun, Val1, Val2);
-                false -> Val1 + Val2
-            end
-        end,
+    ErrorLogger = fun(Reason) -> ?SLOG(info, #{msg => "bad_metrics_value", error => Reason}) end,
     Fun = fun(ElemMap, AccMap) ->
-        emqx_map_lib:merge_with(CombinerFun, ElemMap, AccMap)
+        emqx_map_lib:best_effort_recursive_sum(AccMap, ElemMap, ErrorLogger)
     end,
     lists:foldl(Fun, HeadMetrics, AllMetrics).