I've used reboot for quite a few years to reboot Ubuntu Server, but now the command just puts Ubuntu into some low level, unresponsive state and I have to use the reset button to reboot. I don't have a monitor connected to the server. How can I troubleshoot this?
It began after the last HWE update, where at first it was spurious, but now it's every time I try to reboot.
On my old Dell I had to use
kernel paramenter, hinted from here. Maybe you need a couple of experiments --- my old Dell did not restart every other reboot (!) without the kernel parameter. BIOS mysteries...