Python 3.15.0 release candidate 2 has been published, according to a link post by developer Simon Willison dated 1st September 2026. Hugo van Kemenade, release manager for Python 3.14 and 3.15, announced the candidate, with the final release scheduled for October. Willison quotes the announcement stating that, during the release candidate phase, 'only reviewed code changes which are clear bug fixes are allowed between this release candidate and the final release.' The announcement encourages maintainers of third-party Python projects to prepare their projects for 3.15, publish Python 3.15 wheels on PyPI, and help other projects test. It notes that binary wheels built against 3.15.0 release candidates will work with future versions of Python 3.15. Willison recounts finding a bug in Python 3.10 in 2021 by running his test suites, though not during the RC period, meaning the bug had already shipped; he says he now pays closer attention to release candidates. He notes the new RC is not yet available for GitHub Actions and provides a testing matrix configuration using allow-prereleases and check-latest flags. In an update, Willison reports his Datasette and sqlite-utils projects pass, while his LLM project is blocked waiting for a 3.15 wheel for scikit-learn.
- Python 3.15.0 release candidate 2 was announced, with final release scheduled for October
- Hugo van Kemenade is the release manager for Python 3.14 and 3.15
- During the RC phase, only reviewed bug-fix changes are permitted
- Maintainers are urged to test projects and publish 3.15 wheels on PyPI
- Willison reports Datasette and sqlite-utils pass; LLM is blocked awaiting a scikit-learn 3.15 wheel
What it means for you
Python, the programming language behind most AI tools, is nearing a new version (3.15) due in October. A 'release candidate' is a near-final test build put out so developers can catch bugs before it ships for real. For anyone who doesn't write code, this changes nothing today.
Try this
If you maintain a Python project, add Python 3.15 to your test matrix now using the allow-prereleases flag so you catch breakage before the October release rather than after.
Who should care
Developers and teams who maintain Python libraries or applications, especially those who publish packages others depend on.
Skip this if
You don't write or maintain Python code yourself — this is a routine step in a language release cycle with no consumer impact.
Sources: Simon Willison — read the original