Bdtyktl

I have this on two machines with the same problem. This has only recently started happening -- last couple weeks or so with frequent if not daily updates.

An 18.04 machine is working fine.

No errors in any logs.

Requested in comments:

$ dpkg -l | grep ^ii | grep screensaver

ii  libopengl-xscreensaver-perl           0.05-1build4                               amd64        Perl module for writing OpenGL-based XScreenSaver hacks

ii  mate-screensaver-common               1.20.2-1                                   all          MATE screen saver and locker (common files)

ii  xscreensaver                          5.36-1ubuntu1                              amd64        Screensaver daemon and frontend for X11

ii  xscreensaver-data                     5.36-1ubuntu1                              amd64        Screen saver modules for screensaver frontends

ii  xscreensaver-data-extra               5.36-1ubuntu1                              amd64        Extra screen saver modules for screensaver frontends

ii  xscreensaver-gl                       5.36-1ubuntu1                              amd64        GL(Mesa) screen saver modules for screensaver frontends

ii  xscreensaver-gl-extra                 5.36-1ubuntu1                              amd64        Extra GL(Mesa) screen saver modules for screensaver frontends

ii  xscreensaver-screensaver-bsod         5.36-1ubuntu1                              amd64        BSOD screen saver module from XScreenSaver

ii  xscreensaver-screensaver-dizzy        0.3-3                                      all          Graphics demo that makes you dizzy (XScreenSaver hack)

ii  xscreensaver-screensaver-webcollage   5.36-1ubuntu1                              amd64        Webcollage screen saver module from XScreenSaver

Update after removing mate-screensaver

On one of the 18.10 machines xscreensaver is now working. At some point, for reasons I've forgotten, I'd created a startup desktop file and a service file so I removed the startup.

On the other 18.10 machine it is not working.

The situation now:

 $ dpkg -l | grep ^ii | grep screensaver | grep -v xscreen

 $ 



 $ systemctl --user status xscreensaver

 ● xscreensaver.service - XScreenSaver

    Loaded: loaded (/home/stephen/.config/systemd/user/xscreensaver.service; enabled; vendor preset: enabled)

    Active: active (running) since Sun 2019-02-03 18:00:25 PST; 14h ago

  Main PID: 1264 (xscreensaver)

    CGroup: /user.slice/user-1000.slice/user@1000.service/xscreensaver.service

            └─1264 /usr/bin/xscreensaver -nosplash

At first you should remove other screensavers (MATE Screen Saver in your case) from system to prevent interference:

sudo apt purge mate-screensaver mate-screensaver-common

Then enable XScreeSaver autostart via systemd user's service:

systemctl --user enable xscreensaver.service

systemctl --user start xscreensaver.service

   Note: for debugging you can use systemctl --user status xscreensaver.service.

Then wait for timeout and screensaver activation.