* kube-apiserver: requests to endpoints handled by unavailable extension API servers (as indicated by an `Available` condition of `false` in the registered APIService) now return `503` errors instead of `404` errors. ([#58070](https://github.com/kubernetes/kubernetes/pull/58070), [@weekface](https://github.com/weekface))

- Allows PreStop lifecycle handler's sleep action to have a zero value ([#127094](https://github.com/kubernetes/kubernetes/pull/127094), [@sreeram-venkitesh](https://github.com/sreeram-venkitesh)) [SIG Apps, Node and Testing]

- K8s.io/dynamic-resource-allocation/controller: UnsuitableNodes did not handle a mix of allocated and unallocated claims correctly. ([#120338](https://github.com/kubernetes/kubernetes/pull/120338), [@pohly](https://github.com/pohly)) [SIG Node]

### Other notable changes

- The 404 request handler for the GCE Ingress load balancer now exports prometheus metrics, including:

  - `http_404_request_total` (the number of 404 requests handled)
  - `http_404_request_duration_ms` (the amount of time the server took to respond in ms)

* Fix a scheduler panic due to internal cache inconsistency ([#71063](https://github.com/kubernetes/kubernetes/pull/71063), [@Huang-Wei](https://github.com/Huang-Wei))
* apiserver: fixes handling and logging of panics in REST handlers to prevent crashes ([#71076](https://github.com/kubernetes/kubernetes/pull/71076), [@liggitt](https://github.com/liggitt))

    * Introduce a RuntimeClass v1beta1 API. This new beta API renames `runtimeHandler` to `handler`, makes it a required field, and cuts out the spec (handler is a top-level field).

* Default resourceGroup should be used when the value of annotation azure-load-balancer-resource-group is an empty string. ([#79514](https://github.com/kubernetes/kubernetes/pull/79514), [@feiskyer](https://github.com/feiskyer))
* The CRD handler now properly re-creates stale CR storage to reflect CRD update. ([#79114](https://github.com/kubernetes/kubernetes/pull/79114), [@roycaihw](https://github.com/roycaihw))

- EndpointSlice controller now handles terminating pods correctly and is better at preventing race conditions. ([#89118](https://github.com/kubernetes/kubernetes/pull/89118), [@robscott](https://github.com/robscott)) [SIG Apps and Network]

- Sync node status during kubelet node shutdown.
  Adds an pod admission handler that rejects new pods when the node is in progress of shutting down. ([#98005](https://github.com/kubernetes/kubernetes/pull/98005), [@wzshiming](https://github.com/wzshiming)) [SIG Node]