- Kubeadm: removed preflight check for existence of the conntrack binary, as conntrack is no longer a kube-proxy dependency in version 1.32 and newer. ([#126953](https://github.com/kubernetes/kubernetes/pull/126953), [@aroradaman](https://github.com/aroradaman)) [SIG Cluster...

- Kubeadm: Added support during the preflight check "CreateJob" of "kubeadm upgrade" to check if there are no nodes where a Pod can be scheduled. If there are none, show a warning and skip this preflight check. This can happen in single node clusters where the only node was drained. ([#124503](https://github.com/kubernetes/kubernetes/pull/124503), [@neolit123](https:/...

- Kubeadm: during the preflight check "CreateJob" of "kubeadm upgrade", check if there are no nodes where a Pod can schedule. If there are none, show a warning and skip this preflight check. This can happen in single node clusters where the only node was drained. ([#124570](https://github.com/kubernetes/kubernetes/pull/124570), [@neolit123](https://gi...

                      properties:
                        allowCredentials:
                          description: Indicates whether the caller is allowed to
                            send the actual request (not the preflight) using credentials.
                          nullable: true
                          type: boolean
                        allowHeaders:

### Other (Cleanup or Flake)

- Kubeadm: removed `socat` and `ebtables` from kubeadm preflight checks ([#127415](https://github.com/kubernetes/kubernetes/pull/127415), [@saschagrunert](https://github.com/saschagrunert)) [SIG Cluster Lifecycle]

## Dependencies

### Added
_Nothing has changed._

### Other (Cleanup or Flake)

- Kubeadm: removed `socat` and `ebtables` from kubeadm preflight checks ([#127416](https://github.com/kubernetes/kubernetes/pull/127416), [@saschagrunert](https://github.com/saschagrunert)) [SIG Cluster Lifecycle]

## Dependencies

### Added
_Nothing has changed._

with a content type of `text/plain` containing JSON data would be accepted and the JSON data would be extracted.

But requests with content type `text/plain` are exempt from [CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS) preflights, for being considered [Simple requests](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#simple_requests). So, the browser would execute them right away including cookies, and the text content could be a JSON string that would be parsed and...