* Changed default scsi controller type in vSphere Cloud Provider ([#38426](https://github.com/kubernetes/kubernetes/pull/38426), [@abrarshivani](https://github.com/abrarshivani))
* Fixes API compatibility issue with empty lists incorrectly returning a null `items` field instead of an empty array. ([#39834](https://github.com/kubernetes/kubernetes/pull/39834), [@liggitt](https://github.com/liggitt))

protobuf you will be forced to restore from backup, and you will lose any changes
since you converted to protobuf.  After conversion to protobuf, you should
validate the correct operation of your cluster thoroughly before returning it
to normal operation.

Backups are always a good precaution, particularly around upgrades, but this
upgrade has multiple known issues where the only remedy is to restore from
backup.

* Fix incorrectly propagated ResourceVersion in ListRequests returning 0 items. ([#64150](https://github.com/kubernetes/kubernetes/pull/64150), [@wojtek-t](https://github.com/wojtek-t))

* Protobuf serialization does not distinguish between `[]` and `null`. ([#45294](https://github.com/kubernetes/kubernetes/pull/45294), [@liggitt](https://github.com/liggitt))

   ([#123003](https://github.com/kubernetes/kubernetes/pull/123003), [@alexzielenski](https://github.com/alexzielenski))
- Fixed a non-recursive list returning "resource version too high" error when consistent listing from cache is enabled.
   ([#123674](https://github.com/kubernetes/kubernetes/pull/123674), [@serathius](https://github.com/serathius))

  
  **How can I migrate?**
  
  For backward compatibility, nil `QueueingHintFn` is treated as always returning QueueAfterBackoff. 
  So, if you want to just keep the existing behavior, you can register `ClusterEventWithHint` with no `QueueingHintFn` in it. 

* Filter out non-RestartAlways mirror pod in restart test. ([#37203](https://github.com/kubernetes/kubernetes/pull/37203), [@Random-Liu](https://github.com/Random-Liu))
* Validate volume spec before returning azure mounter ([#37018](https://github.com/kubernetes/kubernetes/pull/37018), [@rootfs](https://github.com/rootfs))

* fixes a panic applying json patches containing out of bounds operations ([#64355](https://github.com/kubernetes/kubernetes/pull/64355), [@liggitt](https://github.com/liggitt))
* Fix incorrectly propagated ResourceVersion in ListRequests returning 0 items. ([#64150](https://github.com/kubernetes/kubernetes/pull/64150), [@wojtek-t](https://github.com/wojtek-t))

- Kube-apiserver: fixed a bug returning inconsistent results from list requests which set a field or label selector and set a paging limit ([#94002](https://github.com/kubernetes/kubernetes/pull/94002), [@wojtek-t](https://github.com/wojtek-t)) [SIG API Machinery]

* Protobuf serialization does not distinguish between `[]` and `null`.
API fields previously capable of storing and returning either `[]` and `null` via JSON API requests (for example, the Endpoints `subsets` field)
can now store only `null` when created using the protobuf content-type or stored in etcd using protobuf serialization (the default in 1.6).