*  - KUBE_SSH_KEY (for skeleton provider) was previously assumed to be a filename relative to ~/.ssh but can now also be an absolute path

### Other notable changes

* sysctl support is now considered beta ([ref](https://github.com/kubernetes/enhancements/issues/34))
* Support for Azure Virtual Machine Scale Sets is now considered beta. ([ref](https://github.com/kubernetes/enhancements/issues/513))
* Azure support for Cluster Autoscaler is now considered beta. ([ref](https://github.com/kubernetes/enhancements/issues/514))

  - kubeadm now handles air-gapped environments by using the local client version as a fallback.
  - Some kubeadm commands are now allowed to work in a completely offline mode.
- Certificate handling improvements:
  - Renew certs as part of upgrade.
  - New `kubeadm alpha phase certs renew` command for renewing certificates.
  - Certificates created with kubeadm now have improved uniqueness of Distinguished Name fields.

- Kubectl [get and describe](https://github.com/kubernetes/enhancements/issues/515) now works with extensions
- Nodes now support [third party monitoring plugins](https://github.com/kubernetes/enhancements/issues/606).
- A new [Scheduling Framework](https://github.com/kubernetes/enhancements/issues/624) for schedule plugins is now Alpha.

*   The "ServiceNodeExclusion" feature gate must now be enabled for the `alpha.service-controller.kubernetes.io/exclude-balancer` annotation on nodes to be honored. ([#54644](https://github.com/kubernetes/kubernetes/pull/54644),[ @brendandburns](https://github.com/brendandburns))

### **Scheduling**

*   Taint key `unreachable` is now in GA.
*   Taint key `notReady` is changed to `not-ready`, and is also now in GA.

    * The help message for missingResourceError is now generic ([#45582](https://github.com/kubernetes/kubernetes/pull/45582), [@CaoShuFeng](https://github.com/CaoShuFeng))

#### Windows
- The Windows containers RunAsUsername feature is now beta.
- Windows worker nodes in a Kubernetes cluster now support Windows Server version 1903 in addition to the existing support for Windows Server 2019
- The RuntimeClass scheduler can now simplify steering Linux or Windows pods to appropriate nodes

- `kubectl api-resources` now prints the API version (as 'API group/version', same as output of `kubectl api-versions`). The column APIGROUP is now APIVERSION ([#95253](https://github.com/kubernetes/kubernetes/pull/95253), [@sallyom](https://github.com/sallyom)) [SIG CLI]

#### CLI Changes

- [alpha] `kubectl` plugins: `kubectl` now allows binary extensibility. You can extend the default set of `kubectl` commands by writing plugins
  that provide new subcommands. Refer to the documentation for more information.

- `kubectl rollout` and `rollback` now support StatefulSet.

- `kubectl scale` now uses the Scale subresource for kinds in the apps/v1beta2 group.

* Kubernetes json deserializer is now case-sensitive to restore compatibility with pre-1.8 servers. ([#65157](https://github.com/kubernetes/kubernetes/pull/65157), [@caesarxuchao](https://github.com/caesarxuchao))
    * If your config files contains fields with wrong case, the config files will be now invalid.