Python 3.15’s final planned release candidate is ready for compatibility tests

Python 3.15’s final planned release candidate gives library maintainers a stable ABI target before the scheduled October release. The series adds explicit lazy imports, new built-in types and profiling improvements, alongside interpreter changes. Testing applications and publishing compatible wheels now can expose dependency problems before users begin upgrading to the final version.

Python Insider · Sep 1, 2026

Why it matters

A practical catch-up item for Python maintainers preparing libraries and deployment pipelines for the next release.

More context

The September 1 announcement schedules the final release for October 1. Download the release candidate from python.org and run your compatibility suite in an isolated environment. The team says wheels built against the release candidates will work with subsequent Python 3.15 versions. Try it for release preparation.

Keep in mind

This remains a preview and is not recommended for production by the release team. 1min has not tested dependency compatibility or reproduced the advertised performance gains.

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