Documenting this mainly for my own benefit, on rare occasions my laptop will not go to sleep (suspend nor hibernate) on Linux (Ubuntu). I hate rebooting, but before I hadn’t dug deep enough to see what the issue was.

This happened again the other day, so I did not reboot, just kept it running on my way home from work. Later I needed to use my USB printer, but nothing happened, not even lsusb showed the device (All I saw were the built-in USB hubs and root device).

The following fixed my issue:

(from )