- The scheduling queue didn't notice any extenders' failures, it could miss some cluster events,
  and it could end up Pods rejected by Extenders stuck in unschedulable pod pool in 5min in the worst-case scenario.
  Now, the scheduling queue notices extenders' failures and requeue Pods rejected by Extenders appropriately. ([#122044](https://github.com/kubernetes/kubernetes/pull/122044), [@sanposhiho](https://github.com/sanposhiho)) [SIG Scheduling]

#### **API Server**

* Scheduler skips pods that use a PVC that either does not exist or is being deleted. ([#55957](https://github.com/kubernetes/kubernetes/pull/55957), [@jsafrane](https://github.com/jsafrane))
* Fixed a garbage collection race condition where objects with ownerRefs pointing to cluster-scoped objects could be deleted incorrectly. ([#57211](https://github.com/kubernetes/kubernetes/pull/57211), [@liggitt](https://github.com/liggitt))

### API Change

## Changelog since v1.18.14

## Changes by Kind

### Bug or Regression

- Fix Azure file share not deleted issue when the namespace is deleted ([#97417](https://github.com/kubernetes/kubernetes/pull/97417), [@andyzhangx](https://github.com/andyzhangx)) [SIG Cloud Provider and Storage]

 - For all kinds in the API group version, a spec.selector default value is no longer
 available, because it's incompatible with `kubectl
 apply` and strategic merge patch. You must explicitly set the spec.selector value
 in your manifest. An object with a spec.selector value that does not match the labels in
 its spec.template is invalid.

 - Selector mutation is disabled for all kinds in the

- The scheduling queue didn't notice any extenders' failures, it could miss some cluster events,
  and it could end up Pods rejected by Extenders stuck in unschedulable pod pool in 5min in the worst-case scenario.
  Now, the scheduling queue notices extenders' failures and requeue Pods rejected by Extenders appropriately. ([#122045](https://github.com/kubernetes/kubernetes/pull/122045), [@sanposhiho](https://github.com/sanposhiho)) [SIG Scheduling]

- NodeLifecycleController: When node lease feature is enabled, node lease will be deleted when the corresponding node is deleted. ([#70034](https://github.com/kubernetes/kubernetes/pull/70034), [@wangzhen127](https://github.com/wangzhen127))

### CSI Migration - AzureDisk and vSphere (beta)

  - A namespaced object with an ownerReference referencing a uid of a namespaced kind which does not exist in the same namespace is now consistently treated as though that owner does not exist, and the child object is deleted.