diff --git a/apps/emqx_bridge/src/emqx_bridge_api.erl b/apps/emqx_bridge/src/emqx_bridge_api.erl
index a71315a27..8bfc9feb1 100644
--- a/apps/emqx_bridge/src/emqx_bridge_api.erl
+++ b/apps/emqx_bridge/src/emqx_bridge_api.erl
@@ -983,15 +983,10 @@ call_operation(NodeOrAll, OperFunc, Args = [_Nodes, BridgeType, BridgeName]) ->
             %% still on an older bpapi version that doesn't support it.
             maybe_try_restart(NodeOrAll, OperFunc, Args);
         {error, timeout} ->
-            ?SERVICE_UNAVAILABLE(<<"Request timeout">>);
+            ?BAD_REQUEST(<<"Request timeout">>);
         {error, {start_pool_failed, Name, Reason}} ->
             Msg = bin(io_lib:format("Failed to start ~p pool for reason ~p", [Name, Reason])),
-            case Reason of
-                nxdomain ->
-                    ?BAD_REQUEST(Msg);
-                _ ->
-                    ?SERVICE_UNAVAILABLE(Msg)
-            end;
+            ?BAD_REQUEST(Msg);
         {error, not_found} ->
             BridgeId = emqx_bridge_resource:bridge_id(BridgeType, BridgeName),
             ?SLOG(warning, #{
diff --git a/apps/emqx_bridge/test/emqx_bridge_api_SUITE.erl b/apps/emqx_bridge/test/emqx_bridge_api_SUITE.erl
index bc27afda2..d8e697987 100644
--- a/apps/emqx_bridge/test/emqx_bridge_api_SUITE.erl
+++ b/apps/emqx_bridge/test/emqx_bridge_api_SUITE.erl
@@ -834,7 +834,8 @@ do_start_stop_bridges(Type, Config) ->
     ),
     BadBridgeID = emqx_bridge_resource:bridge_id(?BRIDGE_TYPE_MQTT, BadName),
     ?assertMatch(
-        {ok, SC, _} when SC == 500 orelse SC == 503,
+        %% request from product: return 400 on such errors
+        {ok, SC, _} when SC == 500 orelse SC == 400,
         request(post, {operation, Type, start, BadBridgeID}, Config)
     ),
     ok = gen_tcp:close(Sock),