* 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))

#### DaemonSet
* [beta] DaemonSet supports history and rollback. See [Performing a Rollback on a DaemonSet](https://kubernetes.io/docs/tasks/manage-daemon/rollback-daemon-set/).

#### Deployments

* `kubectl rollout undo` now returns errors when attempting to rollback a deployment to a non-existent revision ([#70039](https://github.com/kubernetes/kubernetes/pull/70039), [@liggitt](https://github.com/liggitt))
    * `kubectl rollout undo` no longer uses the deprecated extensions/v1beta1 rollback API, which means that Events are no longer emitted when rolling back a deployment

- proxy/transport now supports Content-Encoding: deflate ([#76551](https://github.com/kubernetes/kubernetes/pull/76551), [@JieJhih](https://github.com/JieJhih))
- Admission webhooks are now properly called for `scale` and `deployments/rollback` subresources. ([#76849](https://github.com/kubernetes/kubernetes/pull/76849), [@liggitt](https://github.com/liggitt))

## API Changes

be migrated at the current time using the official Kubernetes procedure.

1.6 will also default to protobuf encoding if using etcd3.  **This change is
irreversible.**  To rollback, you must restore from a backup made before the
protobuf/etcd3 switch, and any changes since the backup will be lost.  As 1.5
does not support protobuf encoding, if you roll back to 1.5 after upgrading to

* 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))

- cpumanager will now rollback state if updateContainerCPUSet failed, indicating that the container start failed. This change will prevent CPU leaks. ([#67430](https://github.com/kubernetes/kubernetes/pull/67430), [@choury](https://github.com/choury))

* `deployments/rollback` is now passed through validation/admission controllers ([#72271](https://github.com/kubernetes/kubernetes/pull/72271), [@jhrv](https://github.com/jhrv))

  This feature will not be fully enabled until a future Kubernetes release (likely to be v1.29), but is added in v1.28 to enable
  safe rollback on downgrade. ([#118339](https://github.com/kubernetes/kubernetes/pull/118339), [@jpbetz](https://github.com/jpbetz)) [SIG API Machinery, Auth, Cloud Provider and Testing]

        UserCQ cq = new UserCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                UserCQ cf = new UserCQ();
                cqLambda.callback(cf);
                list.add(new FilterFunctionBuilder(cf.getQuery(), scoreFunctionBuilder));