* 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]

- Fixed an issue with stuck connections handling error responses ([#71412](https://github.com/kubernetes/kubernetes/pull/71412), [@liggitt](https://github.com/liggitt))
- apiserver: fixed handling and logging of panics in REST handlers ([#71076](https://github.com/kubernetes/kubernetes/pull/71076), [@liggitt](https://github.com/liggitt))

### 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)

- Fixed missing delete events on informer re-lists to ensure all delete events were correctly emitted and using the latest known object state, so that all event handlers and stores always reflect the actual apiserver state as best as possible ([#115620](https://github.com/kubernetes/kubernetes/pull/115620), [@odinuge](https://github.com/odinuge))

- 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]

* Cluster Autoscaler 1.0.0 ([#53005](https://github.com/kubernetes/kubernetes/pull/53005), [@mwielgus](https://github.com/mwielgus))
* Remove the --docker-exec-handler flag. Only native exec handler is supported. ([#52287](https://github.com/kubernetes/kubernetes/pull/52287), [@yujuhong](https://github.com/yujuhong))

* 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))