- kubeadm: added "disable success" and "disable denial" as parameters of the "cache" plugin in the Corefile managed by kubeadm. This is to prevent conflicting responses during CoreDNS cache updates. ([#128359](https://github.com/kubernetes/kubernetes/pull/128359), [@matteriben](https://github.com/matteriben)) [SIG Cluster Lifecycle]

  The API Server will no longer proxy non-101 responses for upgrade requests. This could break proxied backends (such as an extension API server) that respond to upgrade requests with a non-101 response code. ([#92941](https://github.com/kubernetes/kubernetes/pull/92941), [@tallclair](https://github.com/tallclair)) [SIG API Machinery]
 
## Changes by Kind

  - `response.patch` and `response.patchType` are not permitted from validating admission webhooks
  - `apiVersion: "admission.k8s.io/v1"` is required

- Kube-apiserver: redirect responses are no longer returned from backends by default. Set `--aggregator-reject-forwarding-redirect=false` to continue forwarding redirect responses. ([#112193](https://github.com/kubernetes/kubernetes/pull/112193), [@jindijamie](https://github.com/jindijamie)) [SIG API Machinery and Testing]

* Resolves an issue serving aggregated APIs backed by services that respond to requests to `/` with non-2xx HTTP responses ([#79895](https://github.com/kubernetes/kubernetes/pull/79895), [@deads2k](https://github.com/deads2k))

  <mime-type type="application/mbms-msk+xml"/>
  <mime-type type="application/mbms-msk-response+xml"/>
  <mime-type type="application/mbms-protection-description+xml"/>
  <mime-type type="application/mbms-reception-report+xml"/>
  <mime-type type="application/mbms-register+xml"/>
  <mime-type type="application/mbms-register-response+xml"/>
  <mime-type type="application/mbms-user-service-description+xml"/>

error if it is not available.  Clients may request fallback to the normal object by adding a non-qualified mime-type to their `Accept` header like `application/json` - the server will then respond with either the alternate representation if it is supported or the fallback mime-type which is the normal object response. ([#59059](https://github.com/kubernetes/kubernetes/pull/59059), [@smarterclayton](https://github.com/smarterclayton))

* kube-apiserver now uses SSH tunnels for webhooks if...

* Fixes a regression proxying responses from aggregated API servers which could cause watch requests to hang until the first event was received ([#75887](https://github.com/kubernetes/kubernetes/pull/75887), [@liggitt](https://github.com/liggitt))

- Resolves a spurious "Unknown discovery response content-type" error in client-go discovery requests by tolerating extra content-type parameters in API responses ([#117637](https://github.com/kubernetes/kubernetes/pull/117637), [@seans3](https://github.com/seans3)) [SIG API Machinery]

  The API Server will no longer proxy non-101 responses for upgrade requests. This could break proxied backends (such as an extension API server) that respond to upgrade requests with a non-101 response code. ([#92941](https://github.com/kubernetes/kubernetes/pull/92941), [@tallclair](https://github.com/tallclair)) [SIG API Machinery]
 
## Changes by Kind