Why am I getting "Unexpected value ''" error in this GitHub action?

user_712765 0
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I have a GitHub action step like this (extracted from a larger test.yml file):

    steps:
    - name: Parse
      shell: bash
      env:
        TYPE: ${{matrix.package-type}}
        BV: ${{matrix.builder-version}}
        # This comment is line 63, the "#" is in column 9
        NULL: ${{ matrix.beta-version }}
      run: |
        echo TYPE is "$TYPE"
        echo BV is "$BV"
        printf "Null is '%s'\n" "$NULL"

When I run it, I get the following error:

The workflow is not valid. .github/workflows/test.yml (Line: 64, Col: 9): Unexpected value ''

Why is this line invalid? How do I fix it?

github-actions
3 Answers

It turns out there is some quirk in the GitHub action YAML parser that treats NULL as a special token. I guess it parses

NULL: ${{ matrix.beta-version }}

as if it were

'': ${{ matrix.beta-version }}

Changing NULL to null does not help. (Side note, keys to env must be unique when compared in a case-insensitive comparison, meaning you cannot have both FOO and foo, even though the case is preserved when setting the environment variable name.)

The best fix/workaround is to avoid using "NULL" and use something else, like "NIL". However, if you must use "NULL", you can do it by putting it in quotes:

"NULL": ${{ matrix.beta-version }}
user_7127650

If you're using a reusable workflow, make sure you're not passing runs-on to the job that uses the workflow. The runs-on is contained in the workflow file itself, not in the top level job.

The workflow is not valid. .github/workflows/REDACTED.yml (Line: 123, Col: 5): Unexpected value 'uses' .github/workflows/REDACTED.yml (Line: 124, Col: 5): Unexpected value 'with'

Admin1

In my case it was because go-version looked like this in the matrix section:

  matrix:
    go-version: 1.17
    os: [ubuntu-latest, macos-latest]

It needed to be changed to an array: [1.17]

damagednoob_95390
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