Meaning of Error: Unable to find any supported Python versions. in Serverless Functions build.

[zhzhang]

Question

I'm trying to deploy a python serverless function next to a NextJS app.
I have my script within api/solver.py and have Pipfile and Pipfile.lock in the project root, with python version 3.9.
The dependencies are ortools and supabase.

When I push to my branch, the preview build fails at Error: Unable to find any supported Python versions.
However, 3.9 is one of the supported versions.
Have I set up my project structure incorrectly? Do I need to enable python for serverless functions? Are the dependencies causing the issue?
The text of the error message is very opaque and nothing in the docs or previous discussions that I can find suggests a way to begin debugging this.

[dmarcucci]

Which version of Node are you using for your project? You can find it in Settings > General > Node.js Version.

I just switched a project from 18.x to 20.x as I'm trying to get ahead of the early 2025 deprecation date for 18.x.

In 18.x, I have no issue deploying my Edge functions alongside my Python endpoints. In 20.x, however, I get the same error you put above and adding Pipfile does not solve the issue.

[LilySu]

same node<=18 worked

[andrewcastle10]

Also confirming that switching to 18.x worked - thanks for the help y'all

[mchrisman]

I'm not using Node -- just a bare Python file -- so that workaround doesn't help. AazimAnish's "config" section in vercel.json didn't fix it.

[dmarcucci]

@mchrisman

From what I've read elsewhere, it doesn't matter if you are using just Python - you need to set the Node version to 18.x regardless. This can either be done in package.json (per the workaround @amyegan linked to below) or in the settings for the project in the Vercel UI ("Settings" tab then scroll down to "Node.js Version" section and select "18.x" then do a new deploy). In your case, the latter probably makes most sense.

I agree that @AazimAnish comment is irrelevant.

[ndehouche]

Thank you for this. I had the same problem as OP and it fixed it. Still, this fix makes no sense...

[amyegan]

Thanks for reporting this. The engineering team is working on a bugfix now. But you can find a workaround posted in vercel/community#6287 (comment)

[MhdRaihan384]

{
"builds": [{
"src": "youtube_downloader/wsgi.py",
"use": "@vercel/python",
"config": { "maxLambdaSize": "15mb", "runtime": "python3.8" }
}],
"routes": [
{
"src": "/(.*)",
"dest": "youtube_downloader/wsgi.py"
}
]
}

when iam trying to deploy the django project in vercel it giveing me the erorr

WARN! Due to builds existing in your configuration file, the Build and Development Settings defined in your Project Settings will not apply. Learn More: https://vercel.link/unused-build-settings
23:07:27.491 | Error: Unable to find any supported Python versions.
23:07:27.492 | Learn More: http://vercel.link/python-version

[Joshua-AS]

Have you found a solution, I'm having the same error

[dmarcucci]

This issue that @MhdRaihan384 describes is not related to the one mentioned above.

That being said, I think you need to set Python version to either 3.9 or 3.6 as those are the only 2 that Vercel supports at the moment (see here).

3.6 is deprecated, so I would recommend 3.9.