GitHub Actions workflow validation or action reference error

April 30, 2026 · View on GitHub

Playbook ID: github-actions-syntax Category: ci Severity: high Tags: github-actions, yaml, syntax, workflow, ci

What this failure means

GitHub Actions rejected the workflow definition or could not resolve a referenced action, so the workflow could not validate cleanly before the intended job logic ran.

Common log signals

Invalid workflow file
You have an error in your yaml syntax
yaml: line
did not find expected key
mapping values are not allowed here
could not parse the workflow file
error reading
Unrecognized named-value

Diagnosis

GitHub Actions failed while validating the workflow file or resolving a referenced action revision. Common causes include malformed YAML, invalid expressions, and action references that point to a missing tag, branch, or commit.

Fix steps

  1. Validate the workflow locally: pip install yamllint && yamllint .github/workflows/*.yml.
  2. Use the GitHub Actions VS Code extension which provides schema validation in the editor.
  3. Check the exact line number from the error message and inspect indentation carefully.
  4. Ensure expressions like ${{ secrets.TOKEN }} are quoted when they appear in string values.
  5. Verify action references such as uses: actions/checkout@v4 point to a real released ref and are not being truncated or templated into an invalid value.
  6. Verify on: trigger syntax using the GitHub Actions documentation.

Validation

  • Re-run the local reproduction command after the fix.
  • yamllint .github/workflows/
  • actionlint

Likely files to inspect

  • .github/workflows/

Run Faultline

faultline analyze build.log
faultline explain github-actions-syntax
faultline workflow build.log --json --mode agent

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Generated from playbooks/bundled/log/ci/github-actions-syntax.yaml. Do not edit directly — run make docs-generate.