The functions in fxdev_python are now returning 500 Internal Server Error after upgrade to python 3.11

Question

The functions in fxdev_python are now returning 500 Internal Server Error after upgrade to python 3.11

BFM 0

I upgraded my python from 3.9 to 3.11 in my azure function app after seeing this error.

Upgrade your app to newer version as Python 3.9 will reach EOL on 10/31/2025 and will no longer be supported

I followed the below steps from the documentation

Update Python Version in Azure Portal

If your Function App runs on Linux (recommended):

Go to your Function App in the Azure Portal
Under Settings, click Configuration
In General Settings, find:
- Stack → Select Python
- Version → Select the desired version (e.g., 3.11)
Click Save, then restart the app

when i test my functions none seem not to be working. Please help

Krishna Chowdary Paricharla 2,080 Reputation points Microsoft External Staff Moderator

2025-08-07T23:04:54.8366667+00:00
Hello BFM,

The below solution for the 500 Internal Server Error after upgrading to Python 3.11 in your Azure Function App:
Key Fixes:

Use Linux Plan Python 3.11 is only supported on Linux-based plans with Azure Functions v4. Doesn't work on Windows hosting.

Rebuild & Redeploy After upgrading Python, rebuild your virtual environment and redeploy your app. Old Python 3.9 packages may break on 3.11.

Check Logs for Real Error Use Log Stream or App Insights in Azure Portal to view the full error traceback.

Check Package Compatibility Some Python packages may not support Python 3.11 yet. Test locally with python3.11 and pip install -r requirements.txt.

Verify Configuration Settings In Azure Portal → Configuration, ensure:

FUNCTIONS_WORKER_RUNTIME = python

PYTHON_VERSION = 3.11

Deploy a Minimal Function Try deploying a "Hello World" function to confirm the platform works under 3.11.

Restart the App Twice Sometimes Azure caches old settings. Restart twice via Portal or CLI.

Please refer the below documentation:
Troubleshoot Python errors in Azure Functions

Hope this helps!
BFM 0 Reputation points

2025-08-08T14:55:01.38+00:00

@Krishna Chowdary Paricharla :Is it possible to make a copy of our function app and try it.Its my first time doing this.If its possible to make a copy please show me how.Thank you
Krishna Chowdary Paricharla 2,080 Reputation points Microsoft External Staff Moderator

2025-08-11T18:11:49.87+00:00

Hello BFM,

Could you please check the private message and provide the required details for troubleshooting the issue further.

Here is the reference link on how to access & data retention policy of private messages in Microsoft Q&A.

Your answer

Krishna Chowdary Paricharla 2,080 Reputation points Microsoft External Staff Moderator

2025-08-07T23:04:54.8366667+00:00

Hello BFM,

The below solution for the 500 Internal Server Error after upgrading to Python 3.11 in your Azure Function App:
Key Fixes:

Use Linux Plan Python 3.11 is only supported on Linux-based plans with Azure Functions v4. Doesn't work on Windows hosting.

Rebuild & Redeploy After upgrading Python, rebuild your virtual environment and redeploy your app. Old Python 3.9 packages may break on 3.11.

Check Logs for Real Error Use Log Stream or App Insights in Azure Portal to view the full error traceback.

Check Package Compatibility Some Python packages may not support Python 3.11 yet. Test locally with python3.11 and pip install -r requirements.txt.

Verify Configuration Settings In Azure Portal → Configuration, ensure:

FUNCTIONS_WORKER_RUNTIME = python

PYTHON_VERSION = 3.11

Deploy a Minimal Function Try deploying a "Hello World" function to confirm the platform works under 3.11.

Restart the App Twice Sometimes Azure caches old settings. Restart twice via Portal or CLI.

Please refer the below documentation:
Troubleshoot Python errors in Azure Functions

Hope this helps!
BFM 0 Reputation points

2025-08-08T14:55:01.38+00:00

@Krishna Chowdary Paricharla :Is it possible to make a copy of our function app and try it.Its my first time doing this.If its possible to make a copy please show me how.Thank you
Krishna Chowdary Paricharla 2,080 Reputation points Microsoft External Staff Moderator

2025-08-11T18:11:49.87+00:00

Hello BFM,

Could you please check the private message and provide the required details for troubleshooting the issue further.

Here is the reference link on how to access & data retention policy of private messages in Microsoft Q&A.

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The functions in fxdev_python are now returning 500 Internal Server Error after upgrade to python 3.11

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