Python 3.15.0 candidate 2 has been announced by Hugo van Kemenade, the release manager. This marks the final release candidate phase, where only reviewed bug fixes are permitted before the official release.
Engineers running models or agents should prepare their projects for Python 3.15 during this phase. Publishing wheels on PyPI ensures compatibility and facilitates testing for the final release.
Testing against the RCs is supported via GitHub Actions, with flags to automatically switch to the latest RC version. Some packages, such as Datasette and sqlite-utils, have passed testing, while others like scikit-learn are waiting for a compatible wheel.
This process helps prevent bugs from shipping in the final release, as experienced in previous Python versions. Staying updated during RC phases is recommended for maintaining compatibility.
Source: https://simonwillison.net/2026/Sep/1/python-315-rc-2/