1.Error:
rank.proto: A file with this name is already in the pool.

[E 210422 14:48:32 flask_server:87] grpc request execution failed, details: Couldn't build proto file into descriptor pool!
    Invalid proto descriptor for file "rank.proto":
      rank.proto: A file with this name is already in the pool.

2. Solutions

（1） Check the current protobuf version, assuming it is 3.12.2
pip3 show protobuf

（2）Uninstall this version
pip uninstall protobuf

（3）Use the following to reinstall the corresponding version
pip install --no-binary protobuf protobuf==3.12.2