Azure web app AttributeError: module 'typing' has no attribute '_ClassVar'

Question

Hi,

I try to deploy a streamlit application from github to azure app service. In github I have the folowing files:

• requirements.txt
• myapp.py
• myfile.pkl

Python version : 3.8

On Github, build and deploy run successfully but when i click on the app Service Application URL, I have this error : AttributeError: module 'typing' has no attribute '_ClassVar'

I need help to solve this issue.

Thanks

Answer 1

@GUENBOUR Mohamed ,

Based on the info you have shared, it could indicate that, the 'typing' module in Python 3.8 has a different implementation of the '_ClassVar' attribute than in previous versions.

 

Just to highlight, App Service uses the Gunicorn web server by default. The Apps are run using the Gunicorn WSGI HTTP Server.

 

• If you haven’t done this already, review and update the Python version from the Azure portal.
  ( App Service WebApp> Configuration" tab > General settings, change the version of Python that is being used)
• Review and update the dependencies in your requirements.txt file to ensure that they are compatible with the new version of Python.
• You may try executing the command "pip install -r requirements.txt" separately in the App Service container to see if there are any errors or issues with the modules. Ensure that the requirements.txt file is in root directory.
• I understand you have mentioned, you're leveraging Python 3.8, you may run the following command:
  pip install -r requirements.txt --upgrade

After updating the version of Python and the dependencies, you will need to redeploy your WebApp to Azure App Service.
( Try by pushing the updated code to your GitHub repository and then triggering a new deployment in Azure)

 

• If the issue still persist, review Access diagnostic logs and deployment logs to fetch more info ( as outlined in this doc)

Additional info:

• Other frameworks and web servers
• Configure a Linux Python app for Azure App Service

Kindly let us know how it goes, I'll follow-up with you further.