Python 3.15 reaches its stable release

Python 3.15 is now stable, bringing explicit lazy imports, UTF-8 as the default encoding, and new sentinel and frozendict built-in types. It also adds a dedicated profiling package and a statistical sampling profiler. The release moves beyond the previously covered candidates, while its improved just-in-time compiler still carries an experimental label.

Python Insider · Oct 9, 2026

Why it matters

Python maintainers can begin compatibility testing against the final interpreter rather than relying on release-candidate results.

More context

Try the official release in an isolated environment with your application and extension dependencies. Check code that assumes a locale-specific default encoding. The release notes also describe typing and C API changes, including stable-ABI work for free-threaded builds.

Keep in mind

Stable release status does not make every optional feature or dependency production-ready. The announcement warns that Tk-based applications can hang on macOS 27.0 when opening certain dialogs; that issue is not limited to Python 3.15. We have not benchmarked the interpreter.

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