AttributeError: err.message

[heappro]

I got exception in flex code:

            try:
                operation_definition = validate_request_method_to_operation(
                    request_method=request_method,
                    path_definition=path_definition,
                )
            except ValidationError as err:
>               errors['method'].append(err.message)
E               AttributeError: 'ValidationError' object has no attribute 'message'
/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/flex/validation/response.py:222: AttributeError

I think it should be err.detail or err.messages.