build: drop support for Python 3.9

[MikeMcC399]

Fixes: #60919

Situation

Python version 3.9 reached end of life transition and has moved to the list of Python unsupported versions:

Python version	End of life
3.9	2025-10-31

Build scripts for current release lines should continue to allow using this version for the sake of build environment continuity.

Future Node.js release lines should not include the now unsupported Python 3.9 in build scripts.

Change

Remove Python 3.9 from build scripts. This is a semver-major change.

Similar to #55239 which dropped support for Python 3.8

[MikeMcC399]

Test on Windows 11 25H2 with only Python 3.9.13 installed. Build was correctly rejected:

>.\vcbuild
Looking for Python
Python found in C:\Users\mikem\AppData\Local\Microsoft\WindowsApps\\python.exe
Python 3.9.13
Looking for NASM
Using ClangCL because the Node.js version being compiled is >= 24.
Looking for Visual Studio 2026
Looking for Visual Studio 2022
Found MSVS version 17.0
Found Clang version 19.1.5
configure  --dest-cpu=x64 --clang-cl=19.1.5
[WARNING] A shebang '/bin/sh' was found but does not match any supported template (e.g. '/usr/bin/python'), so it will be treated as an arbitrary command.
[WARNING] To prevent execution of programs that are not Python runtimes, set 'shebang_can_run_anything' to 'false' in your configuration file.
Node.js configure: Found Python 3.9.13...
Please use python3.14 or python3.13 or python3.12 or python3.11 or python3.10.
Failed to create vc project files.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/70604/

[aduh95]

I don't have visibility into https://ci.nodejs.org/ (MikeMcC399 is missing the Overall/Read permission - I'm not a Node.js Collaborator)

That's not the reason, most Collaborators also don't have access due to the security release that have been delayed, see https://nodejs.org/en/blog/vulnerability/december-2025-security-releases#update-17-dec-2025-security-release-target-january-7th.
Unfortunately, that means you have to either trust I reviewed the CI results thoroughly, or wait for the CI to be unlocked once the security releases are out. I don't think it's very likely nodejs/build#4208 will be resolved before then, many project members are taking some time off for the holidays.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/70817/

[nodejs-github-bot]

Commit Queue failed

- Loading data for nodejs/node/pull/61177
✔  Done loading data for nodejs/node/pull/61177
----------------------------------- PR info ------------------------------------
Title      build: drop support for Python 3.9 (#61177)
   ⚠  Could not retrieve the email or name of the PR author's from user's GitHub profile!
Branch     MikeMcC399:drop-python39 -> nodejs:main
Labels     build, author ready, needs-ci, dont-land-on-v20.x, dont-land-on-v22.x, dont-land-on-v24.x, dont-land-on-v25.x
Commits    2
 - build: drop support for Python 3.9
 - add back missing bracket
Committers 1
 - Mike McCready <66998419+MikeMcC399@users.noreply.github.com>
PR-URL: https://github.com/nodejs/node/pull/61177
Fixes: https://github.com/nodejs/node/issues/60919
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Stefan Stojanovic <stefan.stojanovic@janeasystems.com>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>
------------------------------ Generated metadata ------------------------------
PR-URL: https://github.com/nodejs/node/pull/61177
Fixes: https://github.com/nodejs/node/issues/60919
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Stefan Stojanovic <stefan.stojanovic@janeasystems.com>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>
--------------------------------------------------------------------------------
   ℹ  This PR was created on Fri, 26 Dec 2025 13:38:49 GMT
   ✔  Approvals: 6
   ✔  - Antoine du Hamel (@aduh95) (TSC): https://github.com/nodejs/node/pull/61177#pullrequestreview-3613632689
   ✔  - Colin Ihrig (@cjihrig): https://github.com/nodejs/node/pull/61177#pullrequestreview-3613700225
   ✔  - Luigi Pinca (@lpinca): https://github.com/nodejs/node/pull/61177#pullrequestreview-3613828398
   ✔  - Marco Ippolito (@marco-ippolito) (TSC): https://github.com/nodejs/node/pull/61177#pullrequestreview-3615541772
   ✔  - Stefan Stojanovic (@StefanStojanovic): https://github.com/nodejs/node/pull/61177#pullrequestreview-3615608194
   ✔  - Ulises Gascón (@UlisesGascon): https://github.com/nodejs/node/pull/61177#pullrequestreview-3620571392
   ✘  Last GitHub CI failed
   ℹ  Last Full PR CI on 2026-01-15T17:53:43Z: https://ci.nodejs.org/job/node-test-pull-request/70817/
- Querying data for job/node-test-pull-request/70817/
✔  Build data downloaded
   ✔  Last Jenkins CI successful
--------------------------------------------------------------------------------
   ✔  Aborted `git node land` session in /home/runner/work/node/node/.ncu

https://github.com/nodejs/node/actions/runs/21047805954

[nodejs-github-bot]

Commit Queue failed

- Loading data for nodejs/node/pull/61177
✔  Done loading data for nodejs/node/pull/61177
----------------------------------- PR info ------------------------------------
Title      build: drop support for Python 3.9 (#61177)
   ⚠  Could not retrieve the email or name of the PR author's from user's GitHub profile!
Branch     MikeMcC399:drop-python39 -> nodejs:main
Labels     build, author ready, needs-ci, commit-queue-squash, dont-land-on-v20.x, dont-land-on-v22.x, dont-land-on-v24.x, dont-land-on-v25.x
Commits    2
 - build: drop support for Python 3.9
 - add back missing bracket
Committers 1
 - Mike McCready <66998419+MikeMcC399@users.noreply.github.com>
PR-URL: https://github.com/nodejs/node/pull/61177
Fixes: https://github.com/nodejs/node/issues/60919
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Stefan Stojanovic <stefan.stojanovic@janeasystems.com>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>
------------------------------ Generated metadata ------------------------------
PR-URL: https://github.com/nodejs/node/pull/61177
Fixes: https://github.com/nodejs/node/issues/60919
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Stefan Stojanovic <stefan.stojanovic@janeasystems.com>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>
--------------------------------------------------------------------------------
   ℹ  This PR was created on Fri, 26 Dec 2025 13:38:49 GMT
   ✔  Approvals: 6
   ✔  - Antoine du Hamel (@aduh95) (TSC): https://github.com/nodejs/node/pull/61177#pullrequestreview-3613632689
   ✔  - Colin Ihrig (@cjihrig): https://github.com/nodejs/node/pull/61177#pullrequestreview-3613700225
   ✔  - Luigi Pinca (@lpinca): https://github.com/nodejs/node/pull/61177#pullrequestreview-3613828398
   ✔  - Marco Ippolito (@marco-ippolito) (TSC): https://github.com/nodejs/node/pull/61177#pullrequestreview-3615541772
   ✔  - Stefan Stojanovic (@StefanStojanovic): https://github.com/nodejs/node/pull/61177#pullrequestreview-3615608194
   ✔  - Ulises Gascón (@UlisesGascon): https://github.com/nodejs/node/pull/61177#pullrequestreview-3620571392
   ✘  Last GitHub CI failed
   ℹ  Last Full PR CI on 2026-01-15T22:00:51Z: https://ci.nodejs.org/job/node-test-pull-request/70817/
- Querying data for job/node-test-pull-request/70817/
✔  Build data downloaded
   ✔  Last Jenkins CI successful
--------------------------------------------------------------------------------
   ✔  Aborted `git node land` session in /home/runner/work/node/node/.ncu

https://github.com/nodejs/node/actions/runs/21048070546

[aduh95]

Landed in d73c49e