* Added a 'kubeadm config migrate' command to convert old API types to their newer counterparts in the new, supported API types. This is just a client-side tool; it just executes locally without requiring a cluster to be running, operating in much the same way as a Unix pipe that upgrades config files. ([#64232](https://github.com/kubernetes/kubernetes/pull/64232), [@luxas](https://github.com/luxas))

* kubeadm: Fix a bug where `kubeadm join` would wait 5 seconds without doing anything. Now `kubeadm join` executes the tasks immediately. ([#48737](https://github.com/kubernetes/kubernetes/pull/48737), [@mattmoyer](https://github.com/mattmoyer))

* kubeadm: Fix a bug where `kubeadm join` would wait 5 seconds without doing anything. Now `kubeadm join` executes the tasks immediately. ([#48737](https://github.com/kubernetes/kubernetes/pull/48737), [@mattmoyer](https://github.com/mattmoyer))

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- `StartupProbe` is stopped explicity when `successThrethold` is reached. 
  This eliminates the problem that `StartupProbe` is executed more than `successThrethold`. ([#121206](https://github.com/kubernetes/kubernetes/pull/121206), [@mochizuki875](https://github.com/mochizuki875)) [SIG Node]

### Other (Cleanup or Flake)

- For volumes that allow attaches across multiple nodes, attach and detach operations across different nodes are now executed in parallel. ([#88678](https://github.com/kubernetes/kubernetes/pull/88678), [@verult](https://github.com/verult)) [SIG Storage]

- Kubeadm: fix a bug where file copy(backup) could not be executed correctly on Windows platform during upgrade ([#117861](https://github.com/kubernetes/kubernetes/pull/117861), [@SataQiu](https://github.com/SataQiu)) [SIG Cluster Lifecycle]

- For volumes that allow attaches across multiple nodes, attach and detach operations across different nodes are now executed in parallel. ([#89239](https://github.com/kubernetes/kubernetes/pull/89239), [@verult](https://github.com/verult)) [SIG Apps, Node and Storage]

- Kubeadm will cleanup the stale data on best effort basis. Stale data will be removed when each reset phase are executed, default etcd data directory will be cleanup when the `remove-etcd-member` phase are executed. ([#110972](https://github.com/kubernetes/kubernetes/pull/110972), [@chendave](https://github.com/chendave)) [SIG Cluster Lifecycle]

### Feature

- Added 3 new metrics for monitoring async API calls in the scheduler when the `SchedulerAsyncAPICalls` feature gate was enabled:
    - `scheduler_async_api_call_execution_total`: tracks executed API calls by call type and result (success/error)
    - `scheduler_async_api_call_duration_seconds`: histogram of API call execution duration by call type and result