Basically hibernate button doesn't work. The command "pm-hibernate" works. So if my laptop's battery goes to critical level it does not hibernate.
How do I fix it? I've searched a bit but haven't found the solution yet.
enabling hibernate by the steps from https://help.ubuntu.com/lts/ubuntu-help/power-hibernate.html makes hibernate work (without the hibernate package), tested by setting hibernate to the powerbutton action with gnome-tweak-tool.