* kubectl: This client version requires the `apps/v1` APIs, so it will not work against a cluster version older than v1.9.0. Note that kubectl only guarantees compatibility with clusters that are +/-1 minor version away. ([#61419](https://github.com/kubernetes/kubernetes/pull/61419), [@enisoc](https://github.com/enisoc))

- Kubectl version changed to write a warning message to stderr if the client and server version difference exceeds the supported version skew of +/-1 minor version. ([#98250](https://github.com/kubernetes/kubernetes/pull/98250), [@brianpursley](https://github.com/brianpursley)) [SIG CLI]

* etcd3: make gets for previous value in watch serialize-able ([#34089](https://github.com/kubernetes/kubernetes/pull/34089), [@wojtek-t](https://github.com/wojtek-t))
* etcd3: minor cleanups ([#34234](https://github.com/kubernetes/kubernetes/pull/34234), [@wojtek-t](https://github.com/wojtek-t))

* fixes configuration error when upgrading kubeadm from 1.9 to 1.10+ ([#62568](https://github.com/kubernetes/kubernetes/pull/62568), [@liztio](https://github.com/liztio))
    * enforces  kubeadm  upgrading kubernetes from the same major and minor versions as the kubeadm binary.
* Bugfix allowing use of IP-aliases with custom-mode network in GCE setup scripts. ([#62172](https://github.com/kubernetes/kubernetes/pull/62172), [@shyamjvs](https://github.com/shyamjvs))

* Protobuf serialization does not distinguish between `[]` and `null`.

* Add automatic etcd 3.2->3.1 and 3.1->3.0 minor version rollback support to gcr.io/google_container/etcd images. For HA clusters, all members must be stopped before performing a rollback. ([#59298](https://github.com/kubernetes/kubernetes/pull/59298), [@jpbetz](https://github.com/jpbetz))

 - Performance improvements for collections of metrics and summary

### Increase the Kubernetes support window to one year

As of Kubernetes 1.19, bugfix support via patch releases for a Kubernetes minor release has increased from 9 months to 1 year.

- kubeadm: Allow users to skip the kube-proxy init addon phase during init and still be able to join a cluster and perform some other minor operations (but not upgrade). ([#82248](https://github.com/kubernetes/kubernetes/pull/82248), [@rosti](https://github.com/rosti))

    byteCount: Long,
  ) {
    if (byteCount == 0L) return // Avoid double-triggering.

    if (bytesWritten == triggerByteCount) {
      source.skip(byteCount)
      return
    }

    val toWrite = minOf(byteCount, triggerByteCount - bytesWritten)
    bytesWritten += toWrite

    delegate.write(source, toWrite)

    if (bytesWritten == triggerByteCount) {
      trigger()
    }

### SIG Network

For 1.13, the areas of focus were in IPv6, DNS improvements and some smaller items: