- kubeadm no longer dumps backtrace if it fails to remove the running containers on reset. ([#73951](https://github.com/kubernetes/kubernetes/pull/73951), [...

- Correct a reference to a not/no longer used kustomize subcommand in the documentation ([#82535](https://github.com/kubernetes/kubernetes/pull/82535), [@demobox](https://github.com/demobox))

    *   Federation-specific behavior will no longer be included in kubectl
    *   kubefed will no longer be released as part of Kubernetes
    *   The Federation servers will no longer be included in the hyperkube binary and image. ([#53816](https://github.com/kubernetes/kubernetes/pull/53816),[ @marun](https://github.com/marun))

### **Node**

- `Kubectl set resources` will no longer return an error if passed an empty change for a resource. `kubectl set subject` will no longer return an error if passed an empty change for a resource. ([#85490](https://github.com/kubernetes/kubernetes/pull/85490), [@sallyom](https://github.com/sallyom)) [SIG CLI]

you MUST read this before you upgrade)

- Kube-proxy's IPVS proxy mode no longer sets the net.ipv4.conf.all.route_localnet sysctl parameter. Nodes upgrading will have net.ipv4.conf.all.route_localnet set to 1 but new nodes will inherit the system default (usually 0). If you relied on any behavior requiring net.ipv4.conf.all.route_localnet, you must set ensure it is enabled as kube-proxy will no longer set it automatically. This change helps to further mitigate CVE-2020-8558. ([#92938]...

- The `WatchFromStorageWithoutResourceVersion` feature was deprecated and can no longer be enabled. ([#129930](https://github.com/kubernetes/kubernetes/pull/129930), [@serathius](https://github.com/serathius))

  without risking breaking old clients, such as controllers.

- `kubectl delete` no longer scales down workload API objects before deletion.
  Users who depend on ordered termination for the Pods of their StatefulSets
  must use `kubectl scale` to scale down the StatefulSet before deletion.

- `kubectl run --env` no longer supports CSV parsing. To provide multiple environment

* Self hosted is no longer supported in the standard workflow. The feature flags have been removed and your self hosted cluster is no longer able to upgrade via kubeadm. ([#69878](https://github.com/kubernetes/kubernetes/pull/69878), [@Klaven](https://github.com/Klaven))

### API Machinery

* The Namespace API object no longer supports the deletecollection operation. ([#46407](https://github.com/kubernetes/kubernetes/pull/46407), [@liggitt](https://github.com/liggitt))

- API
  - Ingress resources will no longer be served from `extensions/v1beta1` in v1.19. Migrate use to the `networking.k8s.io/v1beta1` API, available since v1.14. Existing persisted data can be retrieved via the `networking.k8s.io/v1beta1` API.