- Kubeadm: support automatic retry after failing to pull image ([#86899](https://github.com/kubernetes/kubernetes/pull/86899), [@SataQiu](https://github.com/SataQiu)) [SIG Cluster Lifecycle]
- Kubeadm: upgrade supports fallback to the nearest known etcd version if an unknown k8s version is passed ([#88373](https://github.com/kubernetes/kubernetes/pull/88373), [@SataQiu](https://github.com/SataQiu)) [SIG Cluster Lifecycle]

  - Better detection of installed CRI.
  - Better output for image pull errors.
- Improved air-gapped and offline support
  - kubeadm now handles air-gapped environments by using the local client version as a fallback.
  - Some kubeadm commands are now allowed to work in a completely offline mode.
- Certificate handling improvements:
  - Renew certs as part of upgrade.

  The `EventsToRegister` in `EnqueueExtension` changed the return value from `ClusterEvent` to `ClusterEventWithHint`. `ClusterEventWithHint` allows each plugin to filter out more useless events via the callback function named `QueueingHintFn`.

* kube-scheduler now fallbacks to emitting events using core/v1 Events when events.k8s.io/v1beta1 is disabled. ([#83692](https://github.com/kubernetes/kubernetes/pull/83692), [@yastij](https://github.com/yastij))

;g=meta.k8s.io;v1=v1beta1`.  Older servers will ignore this representation or return an error if it is not available.  Clients may request fallback to the normal object by adding a non-qualified mime-type to their `Accept` header like `application/json` - the server will then respond with either the alternate representation if it is supported or the fallback mime-type which is the normal object response. ([#59059](https://github.com/kubernetes/kubernetes/pull/59059), [@smarterclayton](https://gi...

- Fallback from OpenAPI V3 to V2 when the OpenAPI V3 document is invalid or incomplete. ([#117980](https://github.com/kubernetes/kubernetes/pull/117980), [@seans3](https://github.com/seans3)) [SIG CLI]

* Add automatic etcd 3.2->3.1 and 3.1->3.0 minor version rollback support to gcr.io/google_container/etcd images. For HA clusters, all members must be stopped before performing a rollback. ([#59298](https://github.com/kubernetes/kubernetes/pull/59298), [@jpbetz](https://github.com/jpbetz))

* `kubectl rollout undo` now returns errors when attempting to rollback a deployment to a non-existent revision ([#70039](https://github.com/kubernetes/kubernetes/pull/70039), [@liggitt](https://github.com/liggitt))
    * `kubectl rollout undo` no longer uses the deprecated extensions/v1beta1 rollback API, which means that Events are no longer emitted when rolling back a deployment

* Fix scheduler crashes when Prioritize Map function returns error. ([#69618](https://github.com/kubernetes/kubernetes/pull/69618), [@DylanBLE](https://github.com/DylanBLE))
* Add fallbacks to ARM API when getting empty node IP from Azure IMDS ([#69077](https://github.com/kubernetes/kubernetes/pull/69077), [@feiskyer](https://github.com/feiskyer))

  - `kube-apiserver` now only aggregates openapi schemas from `/openapi/v2` endpoints of aggregated API servers. The fallback to aggregate from `/swagger.json` has been removed. Ensure aggregated API servers provide schema information via `/openapi/v2` (available since v1.10). ([#73441](https://github.com/kubernetes/kubernetes/pull/73441), [@roycaihw](https://github.com/roycaihw))...