Error when evaluating 'runs-on' for job '...'. .github/workflows/....yaml (Line: 39, Col: 14): Unexpected value ''

[jsoref]

Why are you starting this discussion?

Product Feedback

What GitHub Actions topic or product is this about?

Workflow Configuration

Discussion Details

I want to underscore that this is a horrible user experience.

Annotations
2 errors
Image CI Build
Error when evaluating 'runs-on' for job 'build-and-push-prs'. .github/workflows/build-images-ci.yaml (Line: 39, Col: 14): Unexpected value ''
Image CI Build
Error when evaluating 'runs-on' for job 'build-and-push-prs'. .github/workflows/build-images-ci.yaml (Line: 39, Col: 14): Unexpected value ''

I have many questions:

• What is this thing talking about?
• Why is it pointing to a random line?
• How did it get where it got to with an empty box and a green thing?
• Why does GitHub think this is a failure when the only job that ran yielded a ✅ ?
• There's of course "what did GitHub want the poor authors to do in order to not confuse me"?, but let's skip that for now and focus on GitHub telling a better story in the error reporting when the GitHub users make a mistake (and we have to assume they made a mistake, since there's a ❌, right?)

https://github.com/check-spelling-sandbox/cilium/blob/51ad25f0d6d288d8e92838f7b019e35a040b3b5a/.github/workflows/build-images-ci.yaml#L52

Is the most likely line.

If you know the answer and don't work for GitHub, please don't help. (As it happens, I do know the answer, but I want to underscore just how lousy this behavior is.)

For the curious, people are welcome to message me on Slack (Cilium, GitHub Security, anywhere you can find me) and I will happily confirm/reject their guesses or give them hints.

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[RHammond2]

I'm also having this error, except it points to the correct line. I get this discussion is to call out the general behavior and have GitHub acknowledge the confusing nature here.

It's also just unclear to me why this setup that's specifically called out in the Actions docs (https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax#example-expanding-configurations) will cause a failed action. Also, a similar configuration for an os and Python matrix works in many other projects I work on, but not this one that I have just converted to a matrixed run.

The below runner fails instantly with the following setup, so anything after doesn't matter. However, this same patterns works in multiple projects, whether or not runs-on comes before or after strategy. Similarly, this setup fails regardless of where runs-on is placed relative to strategy.

name: Testing
on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main, develop]
  schedule:
    - cron: 0 0 * * MON
jobs:
  build:
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest]
        python-version: ['3.11', '3.13']
        optional: [false]
        include:
          - python-version: '3.11'
            optional: true

The returned error message is the same one referenced in the original posting:

Error when evaluating 'runs-on' for job 'build'. .github/workflows/ci.yml (Line: 11, Col: 14): Unexpected value ''

For reference, the failing CI workflow is here: https://github.com/NatLabRockies/H2Integrate/actions/runs/22976451676, though every commit in this PR has failed for the same reason, but is not an issue in a similar setup here: https://github.com/NLRWindSystems/WOMBAT/actions/runs/22835404891/workflow.

[jsoref]

This is your problem:

        include:
          - python-version: '3.11'
            optional: true

        include:
          - python-version: '3.11'
            optional: true
+           os: ubuntu-latest

Compare:

• https://github.com/check-spelling-sandbox/H2Integrate/actions/runs/22979737015
• https://github.com/check-spelling-sandbox/H2Integrate/actions/runs/22979791762

[RHammond2]

Thanks so much, now I definitely get the sentiment behind opening this discussion!

[jsoref]

Obviously actions/runner could have said:

Error when evaluating 'runs-on' for job 'build' (with matrix: { "os": "", "python-version": "3.11", "optional": "true"}). .github/workflows/ci.yml (Line: 11, Col: 14): Unexpected value ''

And then you wouldn't have to ask for help from me.

I'm not sure if you'd get useful help (today) if you enabled actions debugging (I haven't checked and don't really want to at this time).

[RHammond2]

That would be a much more useful error message for debugging! Then neither of us would be here today. in either case, more intuitive error handling would have avoided the need for enabling the actions debugging because it's a pretty straightforward error if you know the context.

[jsoref]

The specific case for my original post is different (and considerably worse). But yes, an approach where actions/runner remembered which fields it checked and at least reported on their values would help most cases.