Python 3.9 is no longer supported
Change effective on 07 January 2026
Python 3.9 reached its upstream end-of-life on 31st October 2025 and so no longer receives upstream bug or security fixes.
In accordance with our Python Version Support Policy, we previously deprecated Python 3.9 support on 8th January 2025 and added a deprecation warning to the build log announcing its end of support.
As of today, Python 3.9 is no longer supported, and so the latest version of the Python buildpacks reject builds of apps using it.
Existing Python 3.9 apps continue to run, however, you must upgrade them to a newer version of Python before you can perform any further builds/code deployments.
Since Python 3.9 is no longer receiving security updates, apps still using it may contain security vulnerabilities. Upgrade them to a newer version of Python as soon as possible.
For more information, see Supported Python Versions.