diff --git a/apps/emqx_connector/src/emqx_connector_ldap.erl b/apps/emqx_connector/src/emqx_connector_ldap.erl
index 6b2dfa6e1..48733b5e9 100644
--- a/apps/emqx_connector/src/emqx_connector_ldap.erl
+++ b/apps/emqx_connector/src/emqx_connector_ldap.erl
@@ -77,8 +77,10 @@ on_start(InstId, #{servers := Servers0,
             {auto_reconnect, reconn_interval(AutoReconn)},
             {servers, Servers}],
     PoolName = emqx_plugin_libs_pool:pool_name(InstId),
-    _ = emqx_plugin_libs_pool:start_pool(PoolName, ?MODULE, Opts ++ SslOpts),
-    {ok, #{poolname => PoolName}}.
+    case emqx_plugin_libs_pool:start_pool(PoolName, ?MODULE, Opts ++ SslOpts) of
+        ok              -> {ok, #{poolname => PoolName}};
+        {error, Reason} -> {error, Reason}
+    end.
 
 on_stop(InstId, #{poolname := PoolName}) ->
     ?SLOG(info, #{msg => "stopping_ldap_connector",
diff --git a/apps/emqx_connector/src/emqx_connector_mongo.erl b/apps/emqx_connector/src/emqx_connector_mongo.erl
index 58ea888a9..8926587cb 100644
--- a/apps/emqx_connector/src/emqx_connector_mongo.erl
+++ b/apps/emqx_connector/src/emqx_connector_mongo.erl
@@ -130,8 +130,10 @@ on_start(InstId, Config = #{mongo_type := Type,
             {options, init_topology_options(maps:to_list(Topology), [])},
             {worker_options, init_worker_options(maps:to_list(NConfig), SslOpts)}],
     PoolName = emqx_plugin_libs_pool:pool_name(InstId),
-    ok = emqx_plugin_libs_pool:start_pool(PoolName, ?MODULE, Opts),
-    {ok, #{poolname => PoolName, type => Type}}.
+    case emqx_plugin_libs_pool:start_pool(PoolName, ?MODULE, Opts) of
+        ok              -> {ok, #{poolname => PoolName, type => Type}};
+        {error, Reason} -> {error, Reason}
+    end.
 
 on_stop(InstId, #{poolname := PoolName}) ->
     ?SLOG(info, #{msg => "stopping_mongodb_connector",
diff --git a/apps/emqx_connector/src/emqx_connector_mysql.erl b/apps/emqx_connector/src/emqx_connector_mysql.erl
index e467e4b0c..548721a93 100644
--- a/apps/emqx_connector/src/emqx_connector_mysql.erl
+++ b/apps/emqx_connector/src/emqx_connector_mysql.erl
@@ -71,8 +71,10 @@ on_start(InstId, #{server := {Host, Port},
                {auto_reconnect, reconn_interval(AutoReconn)},
                {pool_size, PoolSize}],
     PoolName = emqx_plugin_libs_pool:pool_name(InstId),
-    _ = emqx_plugin_libs_pool:start_pool(PoolName, ?MODULE, Options ++ SslOpts),
-    {ok, #{poolname => PoolName}}.
+    case emqx_plugin_libs_pool:start_pool(PoolName, ?MODULE, Options ++ SslOpts) of
+        ok              -> {ok, #{poolname => PoolName}};
+        {error, Reason} -> {error, Reason}
+    end.
 
 on_stop(InstId, #{poolname := PoolName}) ->
     ?SLOG(info, #{msg => "stopping_mysql_connector",
diff --git a/apps/emqx_connector/src/emqx_connector_pgsql.erl b/apps/emqx_connector/src/emqx_connector_pgsql.erl
index 90d1c207e..7dcaf7373 100644
--- a/apps/emqx_connector/src/emqx_connector_pgsql.erl
+++ b/apps/emqx_connector/src/emqx_connector_pgsql.erl
@@ -83,8 +83,10 @@ on_start(InstId, #{server := {Host, Port},
                {pool_size, PoolSize},
                {named_queries, maps:to_list(maps:get(named_queries, Config, #{}))}],
     PoolName = emqx_plugin_libs_pool:pool_name(InstId),
-    _ = emqx_plugin_libs_pool:start_pool(PoolName, ?MODULE, Options ++ SslOpts),
-    {ok, #{poolname => PoolName}}.
+    case emqx_plugin_libs_pool:start_pool(PoolName, ?MODULE, Options ++ SslOpts) of
+        ok              -> {ok, #{poolname => PoolName}};
+        {error, Reason} -> {error, Reason}
+    end.
 
 on_stop(InstId, #{poolname := PoolName}) ->
     ?SLOG(info, #{msg => "stopping postgresql connector",
diff --git a/apps/emqx_connector/src/emqx_connector_redis.erl b/apps/emqx_connector/src/emqx_connector_redis.erl
index 804adbf97..3907e24f9 100644
--- a/apps/emqx_connector/src/emqx_connector_redis.erl
+++ b/apps/emqx_connector/src/emqx_connector_redis.erl
@@ -117,14 +117,16 @@ on_start(InstId, #{redis_type := Type,
     case Type of
         cluster ->
             case eredis_cluster:start_pool(PoolName, Opts ++ [{options, Options}]) of
-                {ok, _} -> ok;
-                {ok, _, _} -> ok;
-                {error, Reason} -> error(connect_redis_cluster_failed, Reason)
+                {ok, _}         -> {ok, #{poolname => PoolName, type => Type}};
+                {ok, _, _}      -> {ok, #{poolname => PoolName, type => Type}};
+                {error, Reason} -> {error, Reason}
             end;
         _ ->
-            _ = emqx_plugin_libs_pool:start_pool(PoolName, ?MODULE, Opts ++ [{options, Options}])
-    end,
-    {ok, #{poolname => PoolName, type => Type}}.
+            case emqx_plugin_libs_pool:start_pool(PoolName, ?MODULE, Opts ++ [{options, Options}]) of
+                ok              -> {ok, #{poolname => PoolName, type => Type}};
+                {error, Reason} -> {error, Reason}
+            end
+    end.
 
 on_stop(InstId, #{poolname := PoolName}) ->
     ?SLOG(info, #{msg => "stopping_redis_connector",
diff --git a/apps/emqx_plugin_libs/src/emqx_plugin_libs_pool.erl b/apps/emqx_plugin_libs/src/emqx_plugin_libs_pool.erl
index 1fd91f06f..d462e3db2 100644
--- a/apps/emqx_plugin_libs/src/emqx_plugin_libs_pool.erl
+++ b/apps/emqx_plugin_libs/src/emqx_plugin_libs_pool.erl
@@ -30,14 +30,15 @@ pool_name(ID) when is_binary(ID) ->
 start_pool(Name, Mod, Options) ->
     case ecpool:start_sup_pool(Name, Mod, Options) of
         {ok, _} ->
-            ?SLOG(info, #{msg => "start_ecpool_ok", pool_name => Name});
+            ?SLOG(info, #{msg => "start_ecpool_ok", pool_name => Name}),
+            ok;
         {error, {already_started, _Pid}} ->
             stop_pool(Name),
             start_pool(Name, Mod, Options);
         {error, Reason} ->
             ?SLOG(error, #{msg => "start_ecpool_error", pool_name => Name,
                            reason => Reason}),
-            error({start_pool_failed, Name, Reason})
+            {error, {start_pool_failed, Name, Reason}}
     end.
 
 stop_pool(Name) ->