* Support for Docker version 1.9.x has been removed
* rkt version 1.23.0+
  * known issues with the rkt runtime are [listed in the Getting Started Guide](http://kubernetes.io/docs/getting-started-guides/rkt/notes/)
* etcd version 3.0.17
## Changelog since v1.6.0-rc.1


### Previous Releases Included in v1.6.0

### Promoted Server Side Unknown Field Validation to Beta

// https://www.iana.org/domains/root/db/gucci.html
gucci

// guge : Charleston Road Registry Inc.
// https://www.iana.org/domains/root/db/guge.html
guge

// guide : Binky Moon, LLC
// https://www.iana.org/domains/root/db/guide.html
guide

// guitars : XYZ.COM LLC
// https://www.iana.org/domains/root/db/guitars.html
guitars

// guru : Binky Moon, LLC

- The alpha Dynamic Resource Allocation gRPC API is still available, but might...

* rkt version 1.23.0+

    * known issues with the rkt runtime are [listed in the Getting Started Guide](https://kubernetes.io/docs/getting-started-guides/rkt/notes/)

* etcd version 3.0.17

* Go version: 1.8.3. [Link to announcement](https://groups.google.com/d/msg/kubernetes-dev/0XRRz6UhhTM/YODWVnuDBQAJ)

- Kubeadm: remove the deprecated "kubeadm alpha kubelet config enable-dynamic" command. To continue using the feature please defer to the guide for "Dynamic Kubelet Configuration" at k8s.io. This change also removes the parent...

or use cri-dockerd if you are relying on Docker Engine as your container runtime.
For more information about ensuring your cluster is ready for this removal, please
see [this guide](https://kubernetes.io/blog/2022/03/31/ready-for-dockershim-removal/).

### Beta APIs Off by Default

[New beta APIs will not be enabled in clusters by default](https://github.com/kubernetes/enhancements/issues/3136).

* kubeadm: add a preflight check that throws a warning if the cgroup driver for Docker on Linux is not "systemd" as per the k8s.io CRI installation guide. ([#73837](https://github.com/kubernetes/kubernetes/pull/73837), [@neolit123](https://github.com/neolit123))

ion`, `CustomResourceDefinition`, `APIService`, `TokenReview`, `SubjectAccessReview`, `CertificateSigningRequest`, `Lease`, `Ingress`, and `IngressClass` APIs. For the full list check out [Deprecated API Migration Guide](https://kubernetes.io/docs/reference/using-api/deprecation-guide/#v1-22) and the blog post [Kubernetes API and Feature Removals In 1.22: Here’s What You Need To Know](https://blog.k8s.io/2021/07/14/upcoming-changes-in-kubernetes-1-22/).

### Kubernetes release cadence...

## Urgent Upgrade Notes 

### (No, really, you MUST read this before you upgrade)

- Deprecated beta APIs scheduled for removal in `v1.26` are no longer served. See https://kubernetes.io/docs/reference/using-api/deprecation-guide/#v1-26 for more information. ([#111973](https://github.com/kubernetes/kubernetes/pull/111973), [@liggitt](https://github.com/liggitt))