* Kubernetes json deserializer is now case-sensitive to restore compatibility with pre-1.8 servers. ([#65157](https://github.com/kubernetes/kubernetes/pull/65157), [@caesarxuchao](https://github.com/caesarxuchao))
    * If your config files contains fields with wrong case, the config files will be now invalid.

* 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

//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

### API Change

- **ACTION REQUIRED** for custom scheduler plugin developers:
  `PodEligibleToPreemptOthers` in the `preemption` interface now includes `ctx` in the parameters.
  Please update your plugins' implementation accordingly. ([#126465](https://github.com/kubernetes/kubernetes/pull/126465), [@googs1025](https://github.com/googs1025)) [SIG Scheduling]

such as those in the <a href="/pkg/sync/"><code>sync</code></a>
and <a href="/pkg/sync/atomic/"><code>sync/atomic</code></a> packages.
</p>

<p>
If you must read the rest of this document to understand the behavior of your program,
you are being too clever.
</p>

<p>
Don't be clever.
</p>

<h3 id="overview">Informal Overview</h3>

<p>
Go approaches its memory model in much the same way as the rest of the language,