After switching from MBR to GPT and updating grub (possibly overwriting my previous configuration, possibly unrelated, but that would be a strange coincidence) on my desktop computer I can no longer suspend my system (Ubuntu 16.04.7).
I first noticed that the "suspend" menu item is gone, and trying from the command line, sudo systemctl suspend returns Failed to suspend system via logind: Sleep verb not supported. pm-suspend does not do anything, pm-is-supported --suspend ; echo $? returns 1 (i.e. not supported).
As suggested in this answer, I checked the contents of /sys/power/disk. It reads [shutdown] reboot suspend so the solutions from there don't seem to apply here. (I also haven't found a secure boot option in my BIOS/UEFI settings but may have missed that.)
How can I fix this? It definitely used to work before.
