In January 2024, GitHub announced the deprecation of macOS 11 and the removal of the runner image by June 2024. The macOS 11 runner image will be removed on 6/28/2024. We recommend updating workflows to use macos-14, macos-13, macos-12, or macos-latest. Reminder emails will be sent to those who have used the macOS 11 runner image in the past 30 days. Jobs using macOS 11 will temporarily fail during scheduled time periods to raise awareness of the upcoming removal.
macOS 11 deprecation and removal
In January 2024, GitHub announced the deprecation of macOS 11 and the removal of the runner image by June 2024. The macOS 11 runner image will be removed on 6/28/2024. We recommend updating workflows to use macos-14, macos-13, macos-12, or macos-latest. Reminder emails will be sent to those who have used the macOS 11 runner image in the past 30 days. Jobs using macOS 11 will temporarily fail during scheduled time periods to raise awareness of the upcoming removal.
https://github.blog/changelog/2024-05-20-actions-upcoming-changes-to-github-hosted-macos-runners/#macos-11-deprecation-and-removal