google-github-actions/deploy-appengine is pinned at "main". We strongly advise against pinning to "@main" as it may be unstable. Please update your GitHub Action YAML from: uses: 'google-github-actions/deploy-appengine@main' to: uses: 'google-github-actions/deploy-appengine@v1' Alternatively, you can pin to any git tag or git SHA in the repository.