diff --git a/paddlehub/commands/serving.py b/paddlehub/commands/serving.py
index 5b941006957efbbd930e36d4ab9de96d562d1cc9..de9c9c01a6b79c6709f32128cf58587d42d97a9c 100644
--- a/paddlehub/commands/serving.py
+++ b/paddlehub/commands/serving.py
@@ -166,7 +166,7 @@ class ServingCommand:
         '''
         Start one PaddleHub-Serving instance by arguments with gunicorn.
         '''
-        module = self.args.modules
+        module = self.modules_info
         if module is not None:
             port = self.args.port
             if is_port_occupied("127.0.0.1", port) is True:
@@ -209,7 +209,7 @@ class ServingCommand:
         '''
         Start one PaddleHub-Serving instance by arguments with flask.
         '''
-        module = self.args.modules
+        module = self.modules_info
         if module is not None:
             port = self.args.port
             if is_port_occupied("127.0.0.1", port) is True:
diff --git a/paddlehub/serving/app_compat.py b/paddlehub/serving/app_compat.py
index 95c85fc8250c5e01d476c1d291a9ed509a7dc54f..88464733de4ef692667e5605c2d1f8eec1156909 100644
--- a/paddlehub/serving/app_compat.py
+++ b/paddlehub/serving/app_compat.py
@@ -87,7 +87,7 @@ def predict_v2(module_info: dict, input: dict):
         output = serving_method(**predict_args)
     except Exception as err:
         log.logger.error(traceback.format_exc())
-        return package_result("101", err, "")
+        return package_result("101", str(err), "")
 
     return package_result("000", "", output)