build: support Python 3.15

[MikeMcC399]

Situation

The Python list of supported versions includes Python 3.15 with planned first release date 2026-10-01 moved to 2026-10-09 (see PEP 790).

Node.js defines which versions of Python are supported in the configure script which covers Python 3.10 - 3.14, and currently excludes Python 3.15 for use in building and testing, since it is not yet explicitly listed under acceptable_versions.

Change

Add Python 3.15 to:

• configure &
• android-configure

acceptable_versions is spread over multiple lines to ease future backporting. Adding / removing versions can then be done independently without replacing the whole line. This will however need to be backported once manually before it becomes a benefit. For background see #60874 (comment).

Replace Python 3.14 with Python 3.15 in GitHub Actions workflows.

See Python 3.15 - what's new

Note

Windows configurations for automated installation should be separately updated after this PR has landed.

This change does not materially affect the Python versions used in Jenkins, which are determined by each OS' setup. Running in Jenkins only checks that the addition of Python 3.15 didn't prevent any of the existing lower versions from running.

[nodejs-github-bot]

Review requested:

• @nodejs/actions
• @nodejs/security-wg

[MikeMcC399]

Currently Node.js allows the following, so a manual backport will be needed for 24.x & 22.x to avoid overwriting and dropping the lower versions, which need to be preserved:

Node.js branch	Python versions
main	3.10 - 3.14
26.x	3.10 - 3.14
24.x	3.9 - 3.14
22.x	3.8 - 3.14

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.40%. Comparing base (88ec314) to head (33f0601).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #65750   +/-   ##
=======================================
  Coverage   90.40%   90.40%           
=======================================
  Files         791      791           
  Lines      275991   275991           
  Branches    52984    52977    -7     
=======================================
+ Hits       249500   249502    +2     
- Misses      16907    16908    +1     
+ Partials     9584     9581    -3     

see 33 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/76934/

[gurgunday]

lgtm

[MikeMcC399]

https://www.python.org/downloads/ does not yet offer Python 3.15 for download. There was no 3.15 release on the planned date 2026-10-01. No new planned date has been published so far.

I will continue to monitor the 3.15 release.

There was however an EOL transition of Python 3.10 on 2026-10-01 . I plan to submit a PR to drop support for Python 3.10 in time for the upcoming Node.js 27 release. As in the past, this should not be backported to existing supported release lines. I'm holding back on this right now because submitting it whilst the PR for 3.15 is still pending will cause conflicts, and dropping the support for 3.10 is not urgently needed.

[richardlau]

python/peps#5160 has just pushed the release back another week.

[MikeMcC399]

• When Python 3.15.0rc3 has been set up for download by github.com/actions/python-versions
• I plan to rebase to re-test with 3.15.0rc3.
• PEP 790 shows the new expected 3.15.0 final: Friday, 2026-10-09 as available
• I would expect it would be available from github.com/actions/python-versions on the following next working day, which would be Monday, 2026-10-12, since GitHub has to approve manually and release.
• Unblock PR after final 3.15 release availability and CI tests