},
                        "400": {"description": "Client error level 0"},
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

    * Upgrade OpenAPI 3.1.0, this uses JSON Schema 2020-12.
    * Upgrade Swagger UI to version 5.x.x, that supports OpenAPI 3.1.0.

beta and enabled by default. CustomResourceDefinitions with [structural schemas](https://github.com/kubernetes/enhancements/blob/master/keps/sig-api-machinery/20190425-structural-openapi.md) now publish schemas in the OpenAPI document served at `/openapi/v2`. CustomResourceDefinitions with non-structural schemas have a `NonStructuralSchema` condition added with details about what needs to be corrected in the validation schema. ([#77825](https://github.com/kubernetes/kubernetes/pull/77825), [@royc...

* 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))...

  - The `/swaggerapi/*` schema docs, deprecated since 1.7, have been removed in favor of the /openapi/v2 schema docs. ([#72924](https://github.com/kubernetes/kubernetes/pull/72924), [@liggitt](https://github.com/liggitt))

  - `spec.versions[*].schema.openAPIV3Schema` is now required when creating v1 CustomResourceDefinitions
  - `spec.preserveUnknownFields: true` is disallowed when creating v1 CustomResourceDefinitions; it must be specified within schema definitions as `x-kubernetes-preserve-unknown-fields: true`

- 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.

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))

### **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**