This way, in case there was a breaking change for your code in one of the releases, you can still benefit from the previous upgrades. ✨

### Breaking Changes - Upgrade

* ⬆️ Upgrade Starlette to 0.16.0. PR [#4016](https://github.com/tiangolo/fastapi/pull/4016) by [@tiangolo](https://github.com/tiangolo).

Also upgrades the ranges of optional dependencies:

* `"jinja2 >=2.11.2,<4.0.0"`
* `"itsdangerous >=1.1.0,<3.0.0"`

* kubeadm upgrade no longer races leading to unexpected upgrade behavior on pod restarts ([#62655](https://github.com/kubernetes/kubernetes/pull/62655), [@stealthybox](https://github.com/stealthybox))
    * kubeadm upgrade now successfully upgrades etcd and the controlplane to use TLS
    * kubeadm upgrade now supports external etcd setups
    * kubeadm upgrade can now rollback and restore etcd after an upgrade failure

### Other notable changes

* kubeadm upgrade no longer races leading to unexpected upgrade behavior on pod restarts ([#62655](https://github.com/kubernetes/kubernetes/pull/62655), [@stealthybox](https://github.com/stealthybox))
    * kubeadm upgrade now successfully upgrades etcd and the controlplane to use TLS
    * kubeadm upgrade now supports external etcd setups
    * kubeadm upgrade can now rollback and restore etcd after an upgrade failure

    - [Server binaries](#server-binaries-12)
    - [Node binaries](#node-binaries-12)
  - [Changelog since v1.18.5](#changelog-since-v1185)
  - [Urgent Upgrade Notes](#urgent-upgrade-notes)
    - [(No, really, you MUST read this before you upgrade)](#no-really-you-must-read-this-before-you-upgrade)
  - [Changes by Kind](#changes-by-kind-13)
    - [API Change](#api-change-2)
    - [Bug or Regression](#bug-or-regression-12)

* **Tolerations**

are hence enabled by default. This will be fixed in a future release.
[#38593](https://github.com/kubernetes/kubernetes/issues/38593)
* Federation control plane can be upgraded by updating the image
fields in the `Deployment` specs of the control plane components.
However, federation control plane upgrades were not tested in this
release [38537](https://github.com/kubernetes/kubernetes/issues/38537)

## Notable Changes to Existing Behavior

Updates][major_versions].

This release obsoletes OkHttp 2.x, and all code that uses OkHttp's
`com.squareup.okhttp` package should upgrade to the `okhttp3` package. Libraries
that depend on OkHttp should upgrade quickly to prevent applications from being
stuck on the old version.

 *  **There is no longer a global singleton connection pool.** In OkHttp 2.x,

Some upgrade methods might upgrade etcd from 3.0 to 3.1 automatically when you upgrade from Kubernetes 1.8, unless you specify otherwise. Because [etcd does not support downgrading](https://coreos.com/etcd/docs/latest/upgrades/upgrade_3_1.html), you'll need to either remain on etcd 3.1 or restore from a backup if you want to downgrade back to Kubernetes 1.8.

TLS for secure communication and L7 http-based traffic routing.
     * Graceful Node Shutdown (aka drain) - The new “kubectl drain” command gracefully
evicts pods from nodes in preparation for disruptive operations like kernel
upgrades or maintenance.
     * Custom Metrics for Autoscaling (HorizontalPodAutoscaler API in the Autoscaling
API group): The Horizontal Pod Autoscaling feature now supports custom metrics

* Implemented `kubeadm upgrade plan` for checking whether you can upgrade your cluster to a newer version ([#48899](https://github.com/kubernetes/kubernetes/pull/48899), [@luxas](https://github.com/luxas))
    * Implemented `kubeadm upgrade apply` for upgrading your cluster from one version to an other