The current runner (ubuntu-18.04-x64) was detected as self-hosted because the platform does not match a GitHub-hosted runner image (or that image is deprecated and no longer supported). In such a case, you should install Ruby in the $RUNNER_TOOL_CACHE yourself, for example using https://github.com/rbenv/ruby-build You can take inspiration from this workflow for more details: https://github.com/ruby/ruby-builder/blob/master/.github/workflows/build.yml $ ruby-build 3.1.2 /opt/hostedtoolcache/Ruby/3.1.2/x64 Once that completes successfully, mark it as complete with: $ touch /opt/hostedtoolcache/Ruby/3.1.2/x64.complete It is your responsibility to ensure installing Ruby like that is not done in parallel.

Node.js 12 actions are deprecated. Please update the following actions to use Node.js 16: actions/checkout@v2. For more information see: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.