contains invalid UTF-8 data when parsing a protocol buffer. Use the 'bytes' type if you intend to send raw bytes.

[wenhuiwu]

we are tying use a python grpc clinet to send request to the go server.
the proto param we used has been defined as:
message PbRider {
string speed_param = 28;
};
but we get an error:
contains invalid UTF-8 data when parsing a protocol buffer. Use the 'bytes' type if you intend to send raw bytes.

[acozzette]

String fields are only intended for storing UTF-8 data, so if you need to send non-UTF-8 data then it is best to use a bytes field instead.

[wenhuiwu]

But the data has been changed to type-string on go server, why does the python client cannot parse this data? Maybe the python protobuf should do something to deal with those who contains non-UTF-8 data but defined as string in proto?

[acozzette]

I'm not sure how the Go implementation currently handles this, but at least in C++ we validate that strings are UTF-8 during parsing but not during serialization. So if Go does something similar then it is possible to serialize protos with non-UTF-8 strings, which won't be detected later until that proto is parsed again.

If you need to be able to store non-UTF-8 data in that field then you might want to consider just changing it from a string field to a bytes field, which is usually a safe change to make.