default. With this, updates to the `/status` subresource will disallow updates to all fields other than `.status` (not just `.spec` and `.metadata` as before). Also, `required` and `description` can be used at the root of the CRD OpenAPI validation schema when the `/status` subresource is enabled.

In addition, users can now create multiple versions of CustomResourceDefinitions, but without any kind of automatic conversion, and CustomResourceDefinitions now allow specification of additional...

  - The schema for the alpha `CSINodeInfo` CRD has been split into `spec` and `status` fields, and new fields `status.available` and `status.volumePluginMechanism` added. Clusters using the previous alpha schema must delete and recreate the CRD using the new schema. ([#70515](https://github.com/kubernetes/kubernetes/pull/70515), [@davidz627](https://github.com/davidz627))

- Removed deprecated command `kubectl stop`.

- Kubectl can now use http caching for the OpenAPI schema. The cache
  directory can be configured by passing the `--cache-dir` command line flag to kubectl.
  If set to an empty string, caching is disabled.

- Kubectl now performs validation against OpenAPI schema instead of Swagger 1.2. If
  OpenAPI is not available on the server, it falls back to the old Swagger 1.2.

* kube-apiserver: The `AdmissionConfiguration` type accepted by `--admission-control-config-file` has been promoted to `apiserver.config.k8s.io/v1` with no schema changes. ([#85098](https://github.com/kubernetes/kubernetes/pull/85098), [@liggitt](https://github.com/liggitt))...

* fix GetVolumeLimits log flushing issue ([#69558](https://github.com/kubernetes/kubernetes/pull/69558), [@andyzhangx](https://github.com/andyzhangx))
* kube-apiserver: fixes `procMount` field incorrectly being marked as required in openapi schema ([#69744](https://github.com/kubernetes/kubernetes/pull/69744), [@jessfraz](https://github.com/jessfraz))

- Fixed a bug that prevents kubectl to validate CRDs with schema using x-kubernetes-preserve-unknown-fields on object fields.

- Added new `CRDValidationRatcheting` alpha feature. During a PATCH or UPDATE Validation Ratcheting discards errors thrown by unchanged portions of the resource from most OpenAPI schema validations. ([#118990](https://github.com/kubernetes/kubernetes/pull/118990), [@alexzielenski](https://github.com/alexzielenski))

### API-Machinery

* Fixed webhooks to use the scheme provided in clientConfig, instead of defaulting to http. ([#60943](https://github.com/kubernetes/kubernetes/pull/60943), [@jennybuckley](https://github.com/jennybuckley))

`UnversionedKubeletConfigMap` feature gate to Beta and enabled the feature by default. This implies that 1) for new clusters kubeadm will start using the `kube-system/kubelet-config` naming scheme for the kubelet ConfigMap and RBAC rules, instead of the legacy `kubelet-config-x.yy` naming. 2) during upgrade, kubeadm will only write the new scheme ConfigMap and RBAC objects. To disable the feature you can pass `UnversionedKubeletConfigMap: false` in the kubeadm config for new clusters. For upgrade on existing clusters...

### **CLI**

*   Swagger 1.2 validation is removed for kubectl. The options `--use-openapi` and `--schema-cache-dir` are also removed because they are no longer needed. ([#53232](https://github.com/kubernetes/kubernetes/pull/53232),[ @apelisse](https://github.com/apelisse))

### **Cluster Lifecycle**