Just did the upgrade. Followed directions, updated plugins, stopped array. On reboot, the computer did not detect the usb stick with unraid on it as a bootable device. Rebooted multiple times, same thing. Finally pulled the stick, plugged it into my desktop, confirmed that it was detected there, then put back into the unraid server and then it could detect it. Really weird. It then went through the install and everything appears to be fine now.