Protobuf v4 error - Descriptors cannot be created directly.

Announcement: Azure python function apps pinning protobuf package to v4.x.x directly or indirectly (ex. use another library which requires protobuf v4) malfunction as protobuf v4.x.x introduces breaking changes

Problem: There is breaking change introduced in new protobuf package v4.x.x version, ref at https://github.com/protocolbuffers/protobuf/issues/10064

Azure python function worker currently using protobuf package of v3.x.x version. Since protobuf v4 is released, it is observed many python function apps which pin protobuf to v4.x.x in the requirement.txt are affected. Detailed error logs are as below. Caution, if your function app is affected, please refer to mitigation step section below!!!

 [Information] File "/azure-functions-host/workers/python/3.8/LINUX/X64/azure_functions_worker/protos/shared/NullableTypes_pb2.py", line 38, in <module>
 [Information] _descriptor.FieldDescriptor(
 [Information] File "/home/site/wwwroot/.python_packages/lib/site-packages/google/protobuf/descriptor.py", line 560, in __new__
 [Information] _message.Message._CheckCalledFromGeneratedFile()
 [Error] TypeError: Descriptors cannot not be created directly.
 [Information] If this call came from a _pb2.py file, your generated code is out of date and must be regenerated with protoc >= 3.19.0.
 [Information] If you cannot immediately regenerate your protos, some other possible workarounds are:
 [Information] 1. Downgrade the protobuf package to 3.20.x or lower.
 [Information] 2. Set PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=python (but this will use pure-Python parsing and will be much slower).
 [Information] More information: https://developers.google.com/protocol-buffers/docs/news/2022-05-06#python-updates

Mitigation Two ways to mitigate the issue:

1. Set PYTHON_ISOLATE_WORKER_DEPENDENCIES in AppSetting to 1. (For reference, please check https://docs.microsoft.com/en-us/azure/azure-functions/functions-app-settings#python_isolate_worker_dependencies-preview)
2. For users not requiring protobuf v4.x.x versions in your function app requirement.txt, please pin protobuf >= 3.19.3, == 3.*

[gerardsimons]

Thanks for posting this, it is indeed a terrible error since it only started showing up for me when switching to a Premium function and looking at the logs in the advanced tools … This is an awful awful bug that has caused my company a lot of time and effort, please fix!

[gavin-aguiar]

@gerardsimons we have fixed this bug and is currently being rolled out. Runtime version 4.9.1 will have the fix for this.