Please, tell me if I understand you:
You're asking if you can upgrade the host where Update Manager VM is running ? And that you cannot migrate the VM to another host since there is no cluster in place and no shared storage ?
If your answer is YES for my two questions, I can tell you that you cannot use Update Manager, since you will need put your host in Maintenance Mode and consequently will need to shutdown all VMs running on it, including the Update Manager VM.---
Senior Infrastructure Specialist
Thank you Richardson! I thought that might be the case and appreciate the confirmation. We'll continue to update ESXI manually for now.
You could clone the vm that it is running on and then power on that server on a different server, then problem solved.