[BUG] `AttributeError` on import with protobuf 3.18.1

Willingness to contribute

Yes. I would be willing to contribute a fix for this bug with guidance from the MLflow community.

MLflow version

1.26.1

System information

• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Windows 11
• Python version: 3.9
• yarn version, if running the dev UI: n/a

Describe the problem

With MLflow 1.26.1, I am getting an AttributeError at import when using older versions of protobuf (in my case, 3.18.1) that are still permitted by the conda recipe’s protobuf >=3.7.0 constraint.

This seems to be a relatively new issue that does not impact MLflow 1.26.0; this also only seems to be impacting Windows, as the same environment on Linux machines does not result in failures.

Tracking information

No response

Code to reproduce issue

Create a conda environment on Windows with latest MLflow and an older version of protobuf:

$ conda create -n mlflow-repro python=3.9 mlflow=1.26.1 protobuf=3.18.1
$ conda activate mlflow-repro

Attempt to run mlflow:

$ mlflow

Other info / logs

Traceback (most recent call last):
  File "C:\Users\geniu\mambaforge\envs\mlflow-test\Scripts\mlflow-script.py", line 6, in <module>
    from mlflow.cli import cli
  File "C:\Users\geniu\mambaforge\envs\mlflow-test\lib\site-packages\mlflow\__init__.py", line 32, in <module>
    import mlflow.tracking._model_registry.fluent
  File "C:\Users\geniu\mambaforge\envs\mlflow-test\lib\site-packages\mlflow\tracking\__init__.py", line 8, in <module>
    from mlflow.tracking.client import MlflowClient
  File "C:\Users\geniu\mambaforge\envs\mlflow-test\lib\site-packages\mlflow\tracking\client.py", line 16, in <module>
    from mlflow.entities import Experiment, Run, RunInfo, Param, Metric, RunTag, FileInfo, ViewType
  File "C:\Users\geniu\mambaforge\envs\mlflow-test\lib\site-packages\mlflow\entities\__init__.py", line 6, in <module>
    from mlflow.entities.experiment import Experiment
  File "C:\Users\geniu\mambaforge\envs\mlflow-test\lib\site-packages\mlflow\entities\experiment.py", line 2, in <module>
    from mlflow.entities.experiment_tag import ExperimentTag
  File "C:\Users\geniu\mambaforge\envs\mlflow-test\lib\site-packages\mlflow\entities\experiment_tag.py", line 2, in <module>
    from mlflow.protos.service_pb2 import ExperimentTag as ProtoExperimentTag
  File "C:\Users\geniu\mambaforge\envs\mlflow-test\lib\site-packages\mlflow\protos\service_pb2.py", line 18, in <module>
    from .scalapb import scalapb_pb2 as scalapb_dot_scalapb__pb2
  File "C:\Users\geniu\mambaforge\envs\mlflow-test\lib\site-packages\mlflow\protos\scalapb\scalapb_pb2.py", line 22, in <module>
    options = DESCRIPTOR.extensions_by_name['options']
AttributeError: 'NoneType' object has no attribute 'extensions_by_name'

What component(s) does this bug affect?

• area/artifacts: Artifact stores and artifact logging
• area/build: Build and test infrastructure for MLflow
• area/docs: MLflow documentation pages
• area/examples: Example code
• area/model-registry: Model Registry service, APIs, and the fluent client calls for Model Registry
• area/models: MLmodel format, model serialization/deserialization, flavors
• area/projects: MLproject format, project running backends
• area/scoring: MLflow Model server, model deployment tools, Spark UDFs
• area/server-infra: MLflow Tracking server backend
• area/tracking: Tracking Service, tracking client APIs, autologging

What interface(s) does this bug affect?

• area/uiux: Front-end, user experience, plotting, JavaScript, JavaScript dev server
• area/docker: Docker use across MLflow’s components, such as MLflow Projects and MLflow Models
• area/sqlalchemy: Use of SQLAlchemy in the Tracking Service or Model Registry
• area/windows: Windows support

What language(s) does this bug affect?

• language/r: R APIs and clients
• language/java: Java APIs and clients
• language/new: Proposals for new client languages

What integration(s) does this bug affect?

• integrations/azure: Azure and Azure ML integrations
• integrations/sagemaker: SageMaker integrations
• integrations/databricks: Databricks integrations

[starovoitovs]

Installing protobuf==3.20.1 solved the issue.

[dbczumar]

@charlesbluca Glad that installation from PyPI resolved the issue. It does seem to be a problem with the conda package. I’m going to go ahead and close this issue; hopefully the resolution is useful for others who may encounter the same issue with protobuf installation from conda. Thank you for using MLflow!