I'm on trusty and I can't lock my computer by any means. When I press Super+L or use the Lock button in the panel, the behavior is the same: the screen turns black and if I move the mouse, my desktop pops up again, without ever locking.

I'm on Trusty x86 and I confirmed that if I create a new user account, I can lock the screen in that account. I checked the Lock settings in "Brightness & Lock" and everything is grayed out, as the following screen capture shows. How can I enable the usual system lock again?

enter image description here

1 Answer 1


Do you use Unity Tweak Tool? You might have this option enabled and not even know about it:

enter image description here

  • You're right. How did this get enabled in the first place? I re-enabled locking in UTT and now Ubuntu is locking smoothly again. Thanks.
    – ecc
    Apr 18, 2014 at 21:19
  • If you have a separate home partition it might be because of old settings from previous versions. I'm not really sure.
    – Canha
    Apr 18, 2014 at 21:25
  • 1
    I had the same problem, and could only fix it by installing this tool. The tool could not have caused my issue, but it fixed it.
    – Jeff
    Mar 4, 2016 at 3:57
  • Same issue, same fix (install unity-tweak-tool and disable this option). Thanks!
    – taranaki
    Aug 5, 2016 at 1:30
  • same issue on a new install of 16.04 same solution
    – dartdog
    Sep 26, 2016 at 12:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.