The retirement completes a transition that made Node 24 the default on 16 June. ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION had allowed a temporary return to Node 20; GitHub's final notice removes that route for github.com and GitHub with Data Residency.
Action maintainers are being told to declare node24 in runs.using and publish a new release. Workflow owners need compatible versions of the actions they call. This setting belongs to the JavaScript action's execution metadata, not the Node version a workflow installs for its application's build or tests.
The host requirements also change: Node 24 is incompatible with macOS 13.4 and earlier and lacks official ARM32 support. GitHub says self-hosted runners on those systems are no longer supported. Its notice does not establish a matching retirement date for GitHub Enterprise Server.