## Known Issues

- Concurrently joining control-plane nodes does not work as expected in kubeadm 1.15.0. The feature was planned for release in 1.15.0, but a fix may  come in a follow up patch release.

- Kubeadm: fix panic in the command "kubeadm certs check-expiration" when "/etc/kubernetes/pki" exists but cannot be read. ([#124124](https://github.com/kubernetes/kubernetes/pull/124124), [@carlory](https://github.com/carlory)) [SIG Cluster Lifecycle]

- Fixed a kubelet issue that could result in invalid pod status updates to be sent to the api-server where pods would be reported in a terminal phase but also report a ready condition of true in some cases. ([#110479](https://github.com/kubernetes/kubernetes/pull/110479), [@bobbypage](https://github.com/bobbypage)) [SIG Node and Testing]

### SIG-instrumentation

No feature work, but a large refactoring of metrics-server as well as a number of bug fixes.

### SIG-node

  This bug causes the conformance test "HostPort validates that there is no conflict between pods with same hostPort but different hostIP and protocol" to fail. ([#98838](https://github.com/kubernetes/kubernetes/pull/98838), [@aojea](https://github.com/aojea)) [SIG Network and Node]

### Bug or Regression

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.

Also, please note:
- using `application/vnd.kubernetes.protobuf` as the media storage type for 1.6 is default but not required
- the ability to rollback to etcd2 can be preserved by setting the storage media type flag on `kube-apiserver`

MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Each Recipient is solely responsible for determining the appropriateness of using and distributing the Program and assumes all risks associated with its exercise of rights under this Agreement, including but not limited to the risks and costs of program errors, compliance with applicable laws, damage to or loss of data, programs or equipment, and unavailability or interruption of operations. 6. DISCLAIMER OF LIABILITY EXCEPT AS EXPRESSLY SET FORTH IN THIS...

- '`metav1.LabelSelectors` specified in API objects are now validated to ensure
  they do not contain invalid label values that will error at time of use. Existing
  invalid objects can be updated, but new objects are required to contain valid
  label selectors.'
   ([#113699](https://github.com/kubernetes/kubernetes/pull/113699), [@liggitt](https://github.com/liggitt))

- Kubeadm: warn but do not error out on missing "ca.key" files for root CA, front-proxy CA and etcd CA, during "kubeadm join --control-plane" if the user has provided all certificates, keys and kubeconfig files which require signing with the given CA keys. ([#94988](h...