[Solved] Unable to shutdown PC after new installation or kernel upgrade

While this is not really a LinuxCNC issue it may be useful for users trying to update older hardware.

If your PC no longer shuts down properly but reboots automatically you can try to modify kernel parameters:

$ sudo nano /etc/default/grub

Modify the line to (ie add xhci_hcd.quirks=270336 to the existing parameters like 'quiet' in this example):

Save and run:
$ sudo update grub

Reboot and see if the shutdown now works. If it does not you can repeat the above with values 8192 & 262144


discussion here:
forums.linuxmint.com/viewtopic.php?t=283503

Worked for me on three different machines after updating from kernel 4.x to 6.x.