I've tried to hibernate my HP EliteDesk 800 G1 TWR PC using the command
sudo pm-hibernate which exited with no message, error code 128.
man page for
A return value of 128 means that pm-action tried to put the machine in the requested power state but failed.
Trying to run the same command again hung up my system completely.
free -m, I have 15960 MB RAM and with a 16295 MB swap space, which I think should be sufficient.
Then I found this hardware certification page that says "Hibernate is disabled on this system".
Is there any way I could enable hibernation?