Screen does not lock after inactivity

[hanscees]

Hi,

using
Ubuntu 21.10 mate.
After leaving my computer a while the screen should be locked. However, it is not. It is light greyish and I can vaguely see what windows are open. I usually go to a terminal, type reboot and I can work again. But its a safety risk of course.

Any tips on howto troubleshoot this?
windowskey-L works fine, so there is a lockscreen working.

thanks

[Norbert_X]

It is known issue, solution see at

21.10 screen dim problem

It is a side-effect of bugs in mate-screensaver and mate-menus: Please subscribe to both and mark yourself as affected. Possible workaround is to remove MATE Screensaver and temporary replace it by XScreenSaver: sudo apt-get purge --autoremove mate-screensaver sudo apt-get install xscreensaver systemctl --user enable xscreensaver.service systemctl --user start xscreensaver.service then test it using Ctrl+Alt+L. Reverting to default screensaver is possible by systemctl --user disable …