* For Deployment, ReplicaSet, and DaemonSet, selectors are now immutable when updating via the new `apps/v1beta2` API. For backward compatibility, selectors can still be changed when updating via `apps/v1beta1` or `extensions/v1beta1`. ([#50719](https://github.com/kubernetes/kubernetes/pull/50719), [@crimsonfaith91](https://github.com/crimsonfaith91))

### Bug or Regression

- Aggregate errors when putting vmss
  fix: consolidate logs for instance not found error (#105365, @nilo19) [SIG Cloud Provider]
- Allow CSI drivers to just run offline expansion tests (#102740, @gnufied) [SIG Storage and Testing]

* For Deployment, ReplicaSet, and DaemonSet, selectors are now immutable when updating via the new `apps/v1beta2` API. For backward compatibility, selectors can still be changed when updating via `apps/v1beta1` or `extensions/v1beta1`. ([#50719](https://github.com/kubernetes/kubernetes/pull/50719), [@crimsonfaith91](https://github.com/crimsonfaith91))

* Fix AWS NLB security group updates where valid security group ports were incorrectly removed ([#68422](https://github.com/kubernetes/kubernetes/pull/68422), [@kellycampbell](https://github.com/kellycampbell))
    * when updating a service or when node changes occur.
* Fix scheduling starvation of pods in cluster with large number of unschedulable pods. ([#72619](https://github.com/kubernetes/kubernetes/pull/72619), [@everpeace](https://github.com/everpeace))

- Fix invalid VMSS updates due to incorrect cache ([#89002](https://github.com/kubernetes/kubernetes/pull/89002), [@ArchangelSDY](https://github.com/ArchangelSDY)) [SIG Cloud Provider]
- Fix the VMSS name and resource group name when updating Azure VMSS for LoadBalancer backendPools ([#89337](https://github.com/kubernetes/kubernetes/pull/89337), [@feiskyer](https://github.com/feiskyer)) [SIG Cloud Provider]

- All api-server log request lines in a more greppable format. ([#87203](https://github.com/kubernetes/kubernetes/pull/87203), [@lavalamp](https://github.com/lavalamp)) [SIG API Machinery]
- Azure VMSS LoadBalancerBackendAddressPools updating has been improved with sequential-sync + concurrent-async requests. ([#88699](https://github.com/kubernetes/kubernetes/pull/88699), [@feiskyer](https://github.com/feiskyer)) [SIG Cloud Provider]

* Fix AWS NLB security group updates where valid security group ports were incorrectly removed ([#68422](https://github.com/kubernetes/kubernetes/pull/68422), [@kellycampbell](https://github.com/kellycampbell))
    * when updating a service or when node changes occur.
* Allow for watching objects larger than 1MB given etcd accepts objects of size up to 1.5MB ([#72053](https://github.com/kubernetes/kubernetes/pull/72053), [@wojtek-t](https://github.com/wojtek-t))

* Fix AWS NLB security group updates where valid security group ports were incorrectly removed ([#68422](https://github.com/kubernetes/kubernetes/pull/68422), [@kellycampbell](https://github.com/kellycampbell))
    * when updating a service or when node changes occur.

[kubernetes-server-linux-s390x.tar.gz](https://dl.k8s.io/v1.6.0/kubernetes-server-linux-s390x.tar.gz) | `e15de8896bd84a9b74756adc1a2e20c6912a65f6ff0a3f3dfabc8b463e31d19b`

## WARNING: etcd backup strongly recommended

Before updating to 1.6, you are strongly recommended to back up your etcd data.
Please consult the installation procedure you are using (kargo, kops, kube-up,
kube-aws, kubeadm etc) for specific advice.

    * Openstack cinder v1/v2/auto API support ([#40423](https://github.com/kubernetes/kubernetes/pull/40423), [@mkutsevol](https://github.com/mkutsevol))