Use Python 3.14 as the default Python version for new apps #1984
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Previously if a new app did not specify a Python version (e.g. via a `.python-version` file), then the buildpack would default to the latest Python 3.13 release. Now the buildpack will use the latest Python 3.14 release. This does not affect: * apps that specify an explicit Python version * existing apps that have already had a build using the previous default version (since that version is remembered from one build to the next, via the "version pinning" / "sticky versions" feature). Use-cases involving new apps that aren't compatible with Python 3.14 will now need to specify Python 3.13 explicitly: https://devcenter.heroku.com/articles/python-support#specify-a-python-version However most apps should be compatible, since Python 3.14 was released a couple of months ago (2025-10-07), does not contain significant breaking changes over Python 3.13, and has been happily used by the python-getting-started project since 2025-10-10. See: https://docs.python.org/3.14/whatsnew/3.14.html GUS-W-17595747.
runesoerensen
approved these changes
Dec 4, 2025
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Previously if a new app did not specify a Python version (e.g. via a
.python-versionfile), then the buildpack would default to the latest Python 3.13 release.Now the buildpack will use the latest Python 3.14 release.
This does not affect:
Use-cases involving new apps that aren't compatible with Python 3.14 will now need to specify Python 3.13 explicitly:
https://devcenter.heroku.com/articles/python-support#specify-a-python-version
However most apps should be compatible, since Python 3.14 was released a couple of months ago (2025-10-07), does not contain significant breaking changes over Python 3.13, and has been happily used by the python-getting-started project since 2025-10-10.
See:
https://docs.python.org/3.14/whatsnew/3.14.html
GUS-W-17595747.