Failing to fetch version from manifest when using Ubuntu 26.04 container in a self-hosted runner

[ay0o]

Description:
Starting a couple of hours ago, when running in self-hosted runners and using Ubuntu 26.04 container (container: ubuntu:latest or container: ubuntu:26.04), setup-python is not being able to retrieve the version from the manifest.

For example, Error: The version '3.13' with architecture 'x64' was not found for this operating system..

Downgrading to container: ubuntu:24.04 fixes the issue.

However, what's odd is that when running in GitHub's ubuntu-latest runner, even if using the Ubuntu 26.04 container, it's working.

My self-hosted runners are Amazon Linux but the setup-python is running in the container, so it shouldn't matter the runner OS (in fact, setup-python doesn't work at all in Amazon Linux)

Action version:
v6

Platform:

• Ubuntu
• macOS
• Windows

Runner type:

• Hosted
• Self-hosted

Tools version:
All

Repro steps:

  fail:
    runs-on: [self-hosted]
    container: ubuntu:latest
    steps:
      - uses: actions/setup-python@v6
        with:
          python-version: '3.13'

   success:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/setup-python@v6
         with:
           python-version: '3.13'

   success_2:
     runs-on: ubuntu-latest
     container: ubuntu:latest
     steps:
       - uses: actions/setup-python@v6
         with:
           python-version: '3.13'

  success_3:
    runs-on: [self-hosted]
    container: ubuntu:24.04
    steps:
      - uses: actions/setup-python@v6
        with:
          python-version: '3.13'

Expected behavior:
Working with self-hosted runners and Ubuntu 26.04

Actual behavior:
Only working with Ubuntu 24.04 or Ubuntu 22.04 when using self-hosted runners.

[ay0o]

further debugging this, it looks like in GitHub Ubuntu runners it's working because it's not actually downloading anything. By contrast, my ephemeral runners always download the version.

[ay0o]

btw, it's the same that happened two years ago with the release of Ubuntu 24.04.

Related issue: #854

[mahabaleshwars]

Hi @ay0o,
Thank you for creating this issue. We will investigate it and provide feedback as soon as we have some updates.

[ay0o]

@mahabaleshwars the issue is that 26.04 is missing in https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json

[elomariamin]

issue exists on 25.04 as well !

[HarithaVattikuti]

Hi @ay0o
The release of Python versions for Ubuntu-26.04 is scheduled after the runner image becomes available in the runner-images repository. Thank you for your patience.

[ay0o]

issue exists on 25.04 as well !

this is expected as only LTS versions are supported