I think I've found the problem. In view.py, for each request, I create a grpc channel. A channel takes time to connect to the server. I think if I send grpc request while the channel is not connected to the server, this error will happen. The code is under development. I will change the view.py to reuse the grpc channel. After that, if the error persists, I will use your suggestion and I will inform you about the result. thanks.