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Troubleshoot descriptors cannot not be created directly error

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When using Azure Machine Learning, you may receive the following error:

TypeError: Descriptors cannot not be created directly. If this call came from a _pb2.py file, your generated code is out of date and must be regenerated with protoc 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." It is followed by the proposition to install the appropriate version of protobuf library.

If you cannot immediately regenerate your protos, some other possible workarounds are:
 1. Downgrade the protobuf package to 3.20.x or lower.
 2. Set PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=python (but this will use pure-Python parsing and will be much slower).

You may notice this error specifically when using AutoML.

Cause

This problem is caused by breaking changes introduced in protobuf 4.0.0. For more information, see https://developers.google.com/protocol-buffers/docs/news/2022-05-06#python-updates.

Resolution

For a local development environment or compute instance, install the Azure Machine Learning SDK version 1.42.0.post1 or greater.

pip install azureml-sdk[automl,explain,notebooks]>=1.42.0

For more information on updating an Azure Machine Learning environment (for training or deployment), see the following articles:

To verify the version of your installed SDK, use the following command:

pip show azureml-core

This command should return information similar to Version: 1.42.0.post1.

Tip

If you can't upgrade your Azure Machine Learning SDK installation, you can pin the protobuf version in your environment to 3.20.1. The following example is a conda.yml file that demonstrates how to pin the version:

name: model-env
channels:
  - conda-forge
dependencies:
  - python=3.8
  - numpy=1.21.2
  - pip=21.2.4
  - scikit-learn=0.24.2
  - scipy=1.7.1
  - pandas>=1.1,<1.2
  - pip:
    - inference-schema[numpy-support]==1.3.0
    - xlrd==2.0.1
    - mlflow== 1.26.0
    - azureml-mlflow==1.41.0
    - protobuf==3.20.1

Next steps

For more information on the breaking changes in protobuf 4.0.0, see https://developers.google.com/protocol-buffers/docs/news/2022-05-06#python-updates.

For more information on updating an Azure Machine Learning environment (for training or deployment), see the following articles: