The Python core team has announced the third release candidate, Python 3.15.0rc3, with the stable version set to launch on October 9, 2026. This candidate includes several significant updates, such as explicit lazy imports, the introduction of two new built-in types (frozendict and sentinel), UTF-8 as the default encoding, and performance improvements including a faster JIT. Additionally, the new Tachyon sampling profiler has been introduced, which allows for efficient profiling of running processes. Users are advised to test the new version, especially library maintainers, as there will be no ABI changes, ensuring compatibility with future releases, but they should be cautious of issues with tkinter apps on macOS 27.0
Python 3.15.0rc3 Release Candidate Announced: Stable Release Set for October 9, 2026
Python's core team dropped a surprise third release candidate, 3.15.0rc3, moving the stable build to October 9, 2026. The late candidate folds in last-minute lazy-import fixes, and the team stresses there will be no ABI changes from here on so existing binary wheels stay compatible. Highlights include explicit lazy imports, new frozendict and sentinel types, UTF-8 as the default encoding, a faster JIT, and a new Tachyon sampling profiler. Maintainers are urged to test on CI ahead of launch, though macOS 27.0 users should hold off as tkinter apps like IDLE can hang.
