I use Mate as my desktop environment and I recently upgraded from 16.04 to 18.04.

Since the upgrade, I now have two lock screens. If I lock my screen (Ctrl-Alt-L), I get the expected Mate screensaver, but sometimes when I unlock it I get an additional light blue lock screen, just containing a password field.

I end up having to unlock both to get back to my desktop. The last time this happened, the blue screen didn't show a password field and I had to reboot my machine.

I think the blue lock screen is being fired from a timer, somewhere. If I leave my computer locked for long enough, the blue screen will be waiting for me. However if I briefly lock and unlock my machine, only the Mate screensaver appears.

Any ideas what this is? After researching some similar issues, I tried removing gnome-screensaver, but it hasn't fixed anything.

This question is related, however I upgraded rather than a fresh install. Also I have two lock screens, not three, and I've already removed gnome-screensaver.

  • Hello and welcome to AskUbuntu! Everything points to gnome-screensaver being the culprit. Have you rebooted after uninstalling it? Sep 18, 2018 at 9:08
  • @MrShunz Yup, that was the problem :-) Sep 18, 2018 at 11:20

1 Answer 1


As per comments, gnome-screensaver is interfering and should be uninstalled.

After uninstalling, you should reboot your system as the screensaver is still running in memory.

Probably a logout is enough, but I'm not sure if gnome-screensaver gets killed on logout, so a reboot is safer.

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