The current runner (macos--arm64) 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 2.7.8 /Users/runner/hostedtoolcache/Ruby/2.7.8/arm64 Once that completes successfully, mark it as complete with: $ touch /Users/runner/hostedtoolcache/Ruby/2.7.8/arm64.complete It is your responsibility to ensure installing Ruby like that is not done in parallel.

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: ruby/setup-ruby@250fcd6a742febb1123a77a841497ccaa8b9e939. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.