Nick Holland reported this with a HP T430 Thin Client already in May 2022, and I see the same problem on two of my new firewalls. I was hoping a HDMI dummy plug would work as a workaround, but it doesn't. I'm not sure when or what marks the bsd.upgrade file as -x, but that at least that happens. Is there anything I can do to try to help?
As long as a monitor is attached, sysupgrade works just as intended. -- chs
