I told one of my nodes to enter maintenance mode and it sat for overnight like this:
That screenshot was taken almost exactly 26 hours later. There were no running VMs on the host, nothing on the local datastore, no resyncing or rebuilding objects in vSAN, and lastly nearly zero IO on the network adapters.
I tried canceling the task, it would not cancel.
I rebooted the host, it came back into the cluster with that task still running.
I rebooted my vCenter, and that finally killed the task.
I just built a new environment and was greeted by this error. This fix will likely work on other Dell servers, and the settings may apply to other vendors.
High level is you need to set TPM2 Algorithm Selection to SHA256 in the BIOS. You MIGHT have to turn on Intel TXT, and then enable Secure Boot. This SHOULD NOT impact the ESXi installation, but there is a chance it might. Enabling Secure Boot on a machine with modified or unsigned files carries with it the risk of rendering your machine unbootable with the current ESXi installation.