diff --git a/python/pipeline/dag.py b/python/pipeline/dag.py
index 138a2bac132dd3e8afc8209554efb7da02e32853..1275bc704884f6d497da446d03914e24f62fd8ea 100644
--- a/python/pipeline/dag.py
+++ b/python/pipeline/dag.py
@@ -29,8 +29,9 @@ import json
 from .error_catch import ErrorCatch, CustomException, CustomExceptionCode, ParamChecker, ParamVerify
 from .operator import Op, RequestOp, ResponseOp, VirtualOp
 from .channel import (ThreadChannel, ProcessChannel, ChannelData,
-                      ChannelDataErrcode, ChannelDataType, ChannelStopError,
-                      ProductErrCode)
+                      ChannelDataType, ChannelStopError)
+from .error_catch import  ProductErrCode
+from .error_catch import CustomExceptionCode as ChannelDataErrcode
 from .profiler import TimeProfiler, PerformanceTracer
 from .util import NameGenerator, ThreadIdGenerator, PipelineProcSyncManager
 from .proto import pipeline_service_pb2
diff --git a/python/pipeline/error_catch.py b/python/pipeline/error_catch.py
index 0749134ebfda52712e13473ab4f5d16005ba81eb..d56db57bc0b7f4c454266f7a1102a528fdffb081 100644
--- a/python/pipeline/error_catch.py
+++ b/python/pipeline/error_catch.py
@@ -48,8 +48,9 @@ class CustomExceptionCode(enum.Enum):
 
 class ProductErrCode(enum.Enum):
     """
-    ProductErrCode is a base class for recording business error code. 
-    product developers overwrites this class and extend more error codes. 
+    ProductErrCode is to record business error codes.
+    the ProductErrCode  number ranges from 51 to 99
+    product developers can directly add error code into this class. 
     """
     pass
 
@@ -105,13 +106,13 @@ class ErrorCatch():
                     _LOGGER.error("\nLog_id: {}\n{}Classname: {}\nFunctionName: {}\nArgs: {}".format(log_id, traceback.format_exc(), func.__qualname__, func.__name__, args))
                     split_list = re.split("\n|\t|:", str(e))
                     resp.err_no = int(split_list[3])
-                    resp.err_msg = "Log_id: {}  ErrNo: {}  Error_msg: {}  ClassName: {}  FunctionName: {}".format(log_id, resp.err_no, split_list[9], func.__qualname__ ,func.__name__ )
+                    resp.err_msg = "Log_id: {}  Raise_msg: {}  ClassName: {}  FunctionName: {}".format(log_id, split_list[9], func.__qualname__ ,func.__name__ )
                     is_send_to_user = split_list[-1].replace(" ", "")
                     if is_send_to_user == "True":
                          return (None, resp)
                     else:
                         print("Erro_Num: {} {}".format(resp.err_no, resp.err_msg))
-                        print("Init error occurs. For detailed information, Please look up log by log_id.")
+                        print("Init error occurs. For detailed information. Please look up pipeline.log.wf in PipelineServingLogs by log_id.")
                         kill_stop_process_by_pid("kill", os.getpgid(os.getpid()))
                 except Exception as e:
                     if "log_id" in kw.keys():
@@ -123,7 +124,7 @@ class ErrorCatch():
                     resp = pipeline_service_pb2.Response()
                     _LOGGER.error("\nLog_id: {}\n{}Classname: {}\nFunctionName: {}\nArgs: {}".format(log_id, traceback.format_exc(), func.__qualname__, func.__name__, args))
                     resp.err_no = CustomExceptionCode.UNKNOW.value
-                    resp.err_msg = "Log_id: {}  ErrNo: {}  Error_msg: {}  ClassName: {}  FunctionName: {}".format(log_id, resp.err_no, str(e).replace("\'", ""), func.__qualname__ ,func.__name__ )
+                    resp.err_msg = "Log_id: {}  Raise_msg: {}  ClassName: {}  FunctionName: {}".format(log_id, str(e).replace("\'", ""), func.__qualname__ ,func.__name__ )
                     return (None, resp)
                 else:
                     resp = pipeline_service_pb2.Response()
diff --git a/python/pipeline/operator.py b/python/pipeline/operator.py
index 1950d4c9689711c8be39d9164b5484e54d59b97e..4121e290565ed1a492cdf553de1e66a361fe911a 100644
--- a/python/pipeline/operator.py
+++ b/python/pipeline/operator.py
@@ -36,9 +36,10 @@ else:
 
 from .error_catch import ErrorCatch, CustomException, CustomExceptionCode
 from .proto import pipeline_service_pb2
-from .channel import (ThreadChannel, ProcessChannel, ChannelDataErrcode,
-                      ChannelData, ChannelDataType, ChannelStopError,
-                      ChannelTimeoutError, ProductErrCode)
+from .channel import (ThreadChannel, ProcessChannel,ChannelData, 
+                      ChannelDataType, ChannelStopError, ChannelTimeoutError)
+from .error_catch import  ProductErrCode
+from .error_catch import CustomExceptionCode as ChannelDataErrcode
 from .util import NameGenerator
 from .profiler import UnsafeTimeProfiler as TimeProfiler
 from . import local_service_handler