black screen after longer screen lock

Bug #1320989 reported by Darko Veberic on 2014-05-19

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This bug affects 25 people
Affects Status Importance Assigned to Milestone
elementary OS
light-locker (Ubuntu)

Bug Description

when the xfce desktop is locked for longer time the screen goes black after typing the password to unlock. for shorter times the xfce desktop comes back, but one can already see something is not right since the background usually stays black while the panel is rendered slowly and then after some moments or after the mouse move the background is restored. when the desktop is locked for longer, like several hours with the notebook lid closed, the password prompt lights up correctly, but after entering the password screen goes all black. one can still switch to the VC, i tried to login and killed the xfce locker and the gnome-screensaver but this does not help since going back to the F7 VC still just switches to the black screen. there is no other option than to restart X or reboot from the linux VC.

on my notebook this behavior is observed with both, the nouveau and nvidia drivers.

there is no suspicious behavior seen on top and no related trace left in .xsession-errors or /var/log/Xorg.0.log. the already running applications seem to run unaffected behind this black screen (i can hear skype sounds etc).

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: xfce4-session 4.10.1-3ubuntu5
ProcVersionSignature: Ubuntu 3.13.0-24.47-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.1
Architecture: amd64
CurrentDesktop: XFCE
Date: Mon May 19 20:52:38 2014
InstallationDate: Installed on 2014-05-11 (7 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
SourcePackage: xfce4-session
UpgradeStatus: No upgrade log present (probably fresh install)

after i installed the nvidia drivers i have noticed that the screen lock initializes another x server (the nvidia logo blinked for a short moment). this means that the bug descried above is about the lock screen working normally, goes away after successful login, but then reveals the original desktop which stays black and does not wake up.

is there a way to instruct screen locker not to spawn a new screen and just use the existing one?

affects: xfce4-session (Ubuntu) → light-locker (Ubuntu)
Simon Steinbeiß (ochosi) wrote :

This sounds a bit familiar:
Could you see whether the same fix also works for you? It should definitely fix the issue with closing the lid, not sure what this "waiting for a longer period" problem is...

1. Add the Xubuntu Developers PPA to get the new packages: sudo add-apt-repository ppa:xubuntu-dev/ppa
2. Update package information and update the two crucial packages "sudo apt-get update && sudo apt-get install xfce4-power-manager light-locker-settings"
3. Restart your machine.
4. Open light-locker-settings and make sure "Lock on suspend" is enabled (if it already is, disable and then re-enable it, then hit "Apply").
5. Close your laptop's lid.
6. You should be presented with the unlock screen upon opening the lid, login and you should see your desktop

first of all, i have disabled suspend since it does not work with my hardware, so it's not a wake/thaw issue.

regarding "longer period": (1) tested up to an hour and it unlocks although after longer time the desktop redraw is slow (even the pointer looks kinda spritey). i guess this is caused by heavy swapping that's why i suspect a memory leak. (2) today i have closed the lid (note: no suspend/hibernate) in the morning and when i came back after more than 10 hours, again, i get a normal login screen with my icon but after login the screen switches (flashing briefly the nvidia logo) to black and nothing else. there is no crash, the desktop stuff seems to be running normaly, i can hear skype sounds and browser burning cpu on some ads etc. the only way out is reboot or X kill...

will install the xubuntu-dev ppa now...

Simon Steinbeiß (ochosi) wrote :

What version of lightdm-gtk-greeter are you using?
We did fix a leak in it a longer while ago, but it could practically be anything in your session that's leaking.

So what applications do you have running and what does htop say?

ok, i have added the ppa you suggested and now instead of a black screen i get this pajama striped screen you can see in the attached photo. i can still go to VC and do "service lightdm restart" to login into a fresh xfce...

Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in light-locker (Ubuntu):
status: New → Confirmed
Cody Garver (codygarver) wrote :

Happened to me twice today

Changed in elementaryos:
importance: Undecided → High
milestone: none → freya-0.3.1
Jessica (jessiewings) wrote :

This is also affecting me in elementary OS Freya. Just today, I have:

1. had the system lock when I was away for a few minutes, type my password into the lock screen, and had my desktop come back totally frozen, even the cursor
2. the above, except my desktop didn't seem to come back at all, I just got black. I was able to Ctrl+Alt+F1 and reboot from command line.
3. when resuming from suspend, had the lock screen take an inordinately long time to come up, and after I typed my password into it I got the same black screen. Ctrl+Alt+F1 didn't work this time.

I have a five-year-old HP Pavilion dv6; system settings > about says this about my hardware:

Processor: Quad-Core Intel® Core™ i5 CPU M 540 @ 2.53GHz
Graphics: Intel Corporation Core Processor Integrated Graphics Controller (rev 02)
Advanced Micro Devices, Inc. [AMD/ATI] Madison [Mobility Radeon HD 5650/5750 / 6530M/6550M]

Not using any proprietary drivers, just the ones that came with the OS.

happened to me since using the beta 1 version on both 32 and 64 bit.

about 30 minutes of lockscreen the screen got black and nothing happen. should reboot though.

Igor (igorvolt) wrote :

It's happaned with me. I use Elementary OS Freya soon after I lock screen and monitor get in power save and I try unlock screen, display show me blackscreen. I have Ctrl+Alt+F1 and kill xorg, but it does login with every applications and works closed.

alambike (alambike) wrote :

Same problem here:

Ubuntu 14.04 64bits, xfce desktop

Intel(R) Core(TM)2 CPU T7200 @ 2.00GHz
Advanced Micro Devices, Inc. [AMD/ATI] RV515/M54 [Mobility Radeon X1400]

Using the drivers from system.

After a long sleep (~1h), unlock the user session and the screen got blank.

I send a Ctrl+Alt+supr and session locks again, but what is curious, is that if I unlock with a different user that has not initiated the session, the session starts and the screen works perfectly fine.

But the original session is impossible to reactivate, it's necessary restart xfce4-session.

Nick (nsan1129) wrote :

Same problem, this is not Elementary OS specific. Xubuntu here.

Started happening after I added a 2nd monitor to the system. Both monitors are running from the primary video card, an AMD Radeon R9 280x (on fglrx 15.30.3).

Happens consistently if the primary monitor is powered off when attempting to wake screen from lock/sleep. Also happens at other times inconsistently (I haven't found the pattern).

Sometimes portions of windows and desktop icons are black, depending on the window. Chrome doesn't seem affected, terminal windows are. The panel is always affected (black). Going to panel properties redraws it. `xrefresh` does not.

sengerandu (sengerandu) wrote :

I confirm that this problem affects me too. I have not been able to reproduce it at my will, but it recurs manytimes.

1. Black screen upon login after a long screen lock period (2-3 hours or more).
2. Black screen upon removal of second monitor (from either VGA or HDMI port).
3. Issue more likely to occur when switching from a browser tab with flash or youtube running. Sometimes from presentation screen.

Hardware: Lenovo B40-80 (intel i3-5005, 4GB DDR3 RAM, Broadwell-U Integrated graphics controller)
Software: Elementary 0.4, using processor microcode firmware for intel CPUs (proprietary).

This problem persisted with the default driver too. The screen sometimes rapidly flickered (falsely rendering alternate screens or white screens for few milliseconds). With a change in graphics driver also, this issue has remained.

Aneurin Hall (aneurin-hall) wrote :

I did some independent research into this after smashing into this bug on elementary OS loki: the issues are documented on on the light-locker project page at but the source hasn't been touched since 2015, and the project seems to be in development hell with no developers or projects assuming ownership. the readme states:

> To use light-locker with systemd, you need at least lightdm 1.7.0.
> light-locker doesn't work with lightdm version 1.7.5-1.7.9

loki uses lightdm 1.18.3 so it's at least .11 more broken now. If somebody knows how to ping Sean Davis or the lightdm developer Robert Ancell it couldn't hurt.

in the meantime elementary users can workaround the issue by disabling locking in security panel. Which will allow you to return to your session, but may allow your mates to mess with you.

mIcHy AmRaNe (michyamrane) wrote :

I also have a black screen, and moving the mouse or clicking on a keyboard key doesn't change anything,
on the other hand, entering my password and clicking on entry when the screen is black allows me to login and display the desktop normally

mIcHy AmRaNe (michyamrane) wrote :

i resolved the problem in my personal computer using this command :

sudo mv -v -i /etc/xdg/autostart/at-spi-dbus-bus.desktop /etc/xdg/autostart/at-spi-dbus-bus.desktop.disabled

Any success in fixing this bug or any workarounds? It is super annoying. After connecting the second screen to my video card I started getting these delays. And their length is directly proportional to the time the screen was locked/hibernating.

this issue does not appear on my notebook anymore in ubuntu 18.04 when using lightdm...

kilobyte2007, do you encounter this problem in 18.04? If you are using elementary OS instead, please test the 5.0 Juno Beta.

Changed in light-locker (Ubuntu):
status: Confirmed → Incomplete
Changed in elementaryos:
status: New → Incomplete
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