Black screen on resume in Xubuntu 14.04.1

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

I have had this problem as well when locking the screen on suspend/lid close with Xubuntu 14.04.1 (with all updates applied) while using light-locker for the lock screen.

If using JUST the light-locker-settings, then only one setting is set, and no issue:

Setting "Lock on suspend" in light-locker-settings to On:
xfce4-settings-editor (Channel: xfce4-power-manager)
lock-screen-suspend-hiberate = ticked
logind-handle-lid-switch = unticked

Locks via xflock4 on command line, Whisker "Lock Screen" button, Whisker "Log Out" button then Suspend, and on lid close (if "When laptop lid is closed: Suspend" is set in xfce4-power-manager-settings under "On AC" and "On Battery").

Setting "Lock on suspend" in light-locker-settings to Off:
xfce4-settings-editor (Channel: xfce4-power-manager)
lock-screen-suspend-hiberate = unticked
logind-handle-lid-switch = ticked

Problem occurs when:

Setting "Lock on suspend" in light-locker-settings to Off
THEN
Setting "Lock screen when going for suspend/hibernate" to ticked in All Settings, Power Manager, Extended

xfce4-settings-editor (Channel: xfce4-power-manager)
lock-screen-suspend-hiberate = ticked
logind-handle-lid-switch = ticked

Having both these settings ticked causes a locked black screen on wake, after suspend from closing laptop lid. Pressing power off key - after approx 5 seconds the laptop switches off uncleanly. When switching back on, a disk check is ran.

Solution:

Do NOT use Setting "Lock screen when going for suspend/hibernate" in All Settings, Power Manager, Extended

Set "Lock on suspend" in light-locker-settings to Off, click Apply, then set to On, click Apply.

For users that have uninstalled light-locker and light-locker-settings, and installed xscreensaver - to lock on lid close, both settings need to be set:

xfce4-settings-editor (Channel: xfce4-power-manager)
lock-screen-suspend-hibernate = ticked
logind-handle-lid-swtich = ticked

Question:

Could there be a solution so that both settings CAN'T be set when running light-locker / light-locker-settings (as default), but both settings CAN be set for users that want to use xscreensaver instead of light-locker?

On Dell Latitude D400 It doesn't seem to make any difference what settings are set in either power manager or light-locker. Black screen with frozen mouse appears every time laptop lid is opened after suspend by laptop close. No issue if keyboard "Suspend" key or "Suspend" button from log-off menu clicked before closing the lid. In these cases, the laptop resumes correctly on lid open.

Given the upgrade path from 12.04.4 LTS to 14.04.1 LTS, ANY fix that requires de-installing packages or grep editing of conf files is, in my opinion, completely counter to the Ubuntu ethic. This bug remains a huge inconvenience, I'd go as far as saying a killer issue, for most users. I'm on the verge of rolling back in frustration to 12.04 myself.

An update from the Xubuntu team would be much appreciated.

Please can you run: $ xfconf-query -vl -c xfce4-power-manager

Confirm that you have the following settings:

/xfce4-power-manager/lid-action-on-ac 1
/xfce4-power-manager/lid-action-on-battery 1
/xfce4-power-manager/lock-screen-suspend-hibernate true
/xfce4-power-manager/logind-handle-lid-switch false

If not, please set them via: $ xfce4-settings-editor

On the left, under Channel click xfce4-power-manager, make sure Property:

lid-action-on-ac: set to 1
lid-action-on-battery: set to 1
lock-screen-suspend-hibernate: ticked
logind-handle-lid-switch: unticked

See below for initial settings and changes made to settings editor as requested.

Note dpms changed from true to false as a result of the changes.

No change to behaviour. The laptop still shows a black screen with frozen white mouse cursor on lid-reopen when suspended via lid close. Correct action when suspended via "Suspend" key.

Original settings:

$ xfconf-query -vl -c xfce4-power-manager
/xfce4-power-manager/critical-power-action 4
/xfce4-power-manager/dpms-enabled true
/xfce4-power-manager/dpms-on-ac-off 15
/xfce4-power-manager/dpms-on-ac-sleep 10
/xfce4-power-manager/dpms-on-battery-off 10
/xfce4-power-manager/dpms-on-battery-sleep 5
/xfce4-power-manager/general-notification true
/xfce4-power-manager/hibernate-button-action 1
/xfce4-power-manager/lid-action-on-ac 1
/xfce4-power-manager/lid-action-on-battery 1
/xfce4-power-manager/lock-screen-suspend-hibernate false
/xfce4-power-manager/logind-handle-lid-switch true
/xfce4-power-manager/power-button-action 4
/xfce4-power-manager/show-tray-icon 3
/xfce4-power-manager/sleep-button-action 1

Now changes made as requested set to

/xfce4-power-manager/dpms-enabled false

/xfce4-power-manager/lock-screen-suspend-hibernate true
/xfce4-power-manager/logind-handle-lid-switch true

All other settings the same.

There is no checkbox for logind-handle-lid-switch (??)

Those settings should be:

/xfce4-power-manager/dpms-enabled true
/xfce4-power-manager/lock-screen-suspend-hibernate true
/xfce4-power-manager/logind-handle-lid-switch false

You can also set the values via the command line, if you are having trouble with xfce4-settings-editor:

$ xfconf-query -c xfce4-power-manager -p /xfce4-power-manager/dpms-enabled -s true
$ xfconf-query -c xfce4-power-manager -p /xfce4-power-manager/lock-screen-suspend-hibernate -s true
$ xfconf-query -c xfce4-power-manager -p /xfce4-power-manager/logind-handle-lid-switch -s false

Confirm bug persists with these changes.

Black screen with frozen mouse still appears every time laptop lid is opened after suspend by laptop close. No issue if keyboard "Suspend" key or "Suspend" button from log-off menu clicked before closing the lid.

settings below :

xfconf-query -vl -c xfce4-power-manager
/xfce4-power-manager/critical-power-action 4
/xfce4-power-manager/dpms-enabled true
/xfce4-power-manager/dpms-on-ac-off 15
/xfce4-power-manager/dpms-on-ac-sleep 10
/xfce4-power-manager/dpms-on-battery-off 10
/xfce4-power-manager/dpms-on-battery-sleep 5
/xfce4-power-manager/general-notification true
/xfce4-power-manager/hibernate-button-action 1
/xfce4-power-manager/lid-action-on-ac 1
/xfce4-power-manager/lid-action-on-battery 1
/xfce4-power-manager/lock-screen-suspend-hibernate true
/xfce4-power-manager/logind-handle-lid-switch false
/xfce4-power-manager/power-button-action 4
/xfce4-power-manager/show-tray-icon 3
/xfce4-power-manager/sleep-button-action 1

Please can you state your Xfce Power Manager version:

$ xfce4-power-manager -V

Mine is Xfce Power Manager 1.2.0

Also, please can you try a reboot, then make sure those settings have persisted, and test again?

Settings identical after reboot.

Bug persists.

$ xfce4-power-manager -V

Xfce Power Manager 1.2.0

Where you stated: "There is no checkbox for logind-handle-lid-switch (??)" in xfce4-settings-editor, please can you check again?

The Property logind-handle-lid-switch should be Type Boolean and the Value ticked. If not, what Type is it?

Confirm in the "Xfce-settings-editor : Power Manager --> 'Xfce Power Manager ; Settings for the Xfce Power Manager' GUI there is no checkbox entitled "logind-handle-lid-switch" or anything similar.

(Note that I'm talking about the GUI here, not any use of terminal or anything else)

Boolean Checkboxes exist only for :

General-

-Monitor power management control
-Show notifications to notify about the battery state

AC-

-No checkboxes, only drop downs

On Battery-

-Prefer power savings over performance,
-Spin down hard disks

Extended-

-Lock screen when going for suspend/hibernate

Correction:

AC-
-Spin down hard disks (greyed out as "Put computer to sleep" is set to "Never")

GUI options:

/xfce4-power-manager/lid-action-on-ac 1 = Power Manager, On AC, When laptop lid is closed: Suspend
/xfce4-power-manager/lid-action-on-battery 1 = Power Manager, On Batttery, When laptop lid is closed: Suspend
/xfce4-power-manager/lock-screen-suspend-hibernate true = Power Manager, Extended, Lock screen when going for suspend/hibernate
/xfce4-power-manager/logind-handle-lid-switch false = Whisker menu, All Settings, Light Locker Settings, Lock on suspend: On, Apply - by setting this option, it sets logind-handle-lid-switch to false, and lock-screen-suspend-hibernate to true.

My problem occurred when setting Light Locker Settings, Lock on suspend: Off, Apply then setting Power Manager, Extended, Lock screen when going for suspend/hibernate to ticked - this sets both lock-screen-suspend-hibernate and logind-handle-lid-switch to true and I get a locked black screen on wake, after suspend from closing laptop lid.

If that hasn't fixed it for you, it appears we may have seperate problems but similar symptoms.

As stated above, and confirmed by the joint experience of altering parameters, it doesn't seem to make ANY difference what the light-locker or Power-manager settings are, including the above input. The symptoms are always the same:

"...Black screen with frozen mouse appears EVERY TIME laptop lid is opened after suspend by laptop close. No issue if keyboard "Suspend" key or "Suspend" button from log-off menu clicked before closing the lid."

Certainly none the above suggestions, including the latest post, have made any difference.

My belief is that this is a fundamental problem that hasn't been affected by tweaking the various "power-manager" nor "Light-locker" options, either by terminal tweaks or GUI check-boxes. The initial history of #1303736 mirrors my experience. Unfortunately the remedies presented, including the updates appearing in 14.04.1 have manifestly not fixed the issue despite the headline in http://xubuntu.org/news/xubuntu-14-04-1-released/ pointing to https://bugs.launchpad.net/ubuntu/+source/xubuntu-default-settings/+bug/1303736

One last thing I can think of for you to try:

Whisker menu, All Settings, Light Locker Settings, turn "Lock on suspend" Off, hit Apply, turn "Lock on suspend" On, hit Apply.

Reboot and re-test.

It makes no difference whether light-locker is enabled, disabled, lock set or not or even uninstalled. The bug persists in all settings.

From the symptoms, this is NOT to do with the "Lock" setting. It's to do with the laptop not going into standby properly from laptop lid close. This is what the original #1303736 was about which was supposed to have been fixed as per the release notes.

Input from the Xubuntu team would be much appreciated here

Damian, you probably shouldn't go marking the original bug #1303736 (marked resolved) as a duplicate of this one. The whole point of starting this bug was to differentiate it from the previous one, right?

Indeed... :-)

All input welcome.

advice?

Not sure if this help, but I am using a combination of XFCE/i3 - basically i3 with some xfce applets - and since upgrading to 14.04 I had trouble with i3 exiting normally when I close the lid (i.e. my Window manager dying). It seems closing the lid does not just close the backlight, but shuts down the whole display. Whether systemd is in control or xfce4-power does not seem to matter

I have same problem on my netbook HP Compaq Mini 700EW. Also Xubuntu 14.04.1 LTS

I encountered this bug a while back, but it appeared to be fixed by some update. As of the last set of updates I installed, the bug is now back. I cannot continue working after resume since the screen the completely blank (but the backlight is on).

Xubuntu 14.04.1 LTS 64-bit
Lenovo Thinkpad Edge E125

It's probably also worth noting that manually clicking "Suspend" does not suspend the laptop for me; it just logs off of my session.

However, running pm-suspend *does* work.

Problem also appears on Asus Eee PC 1005HA. To prevent it, it's necessary to wait until the power button LED and the power LED are blinking before closing the lid (after selecting "Standby" from session menu). However, in cases where I forget that or don't have the chance to wait, I assigned

xrandr --output LVDS1 --mode 1024x600 --pos 0x0 --rotate normal

to Win+X which I press if the screen remains black.

Damian, does it make any difference if you kill the running xfce4-power-manager process and then suspend via lid close?

@Thaddäus

I confirm there is no difference if the xfce-power-manager process is killed.

Closing the laptop still results in a black screen with a frozen mouse cursor visible upon laptop re-open. The only recourse from this state is a power-off reboot.

The laptop does not appear to suspend when the lid is closed as it does when the hardware "Suspend" key is pressed or the menu item "Logout-suspend" is clicked. With a lid close there is no immediate disk activity and the power light stays on rather than blinks.

Ok, lets remove some packages one by one. Relog and re-test each time.

1) xfce4-power-manager
2) upower

Also, test if suspend via lid close works properly while not logged in.

@Thaddäus

-With xfce-power-manager installed as shipped:

Simply logging off provokes the back screen symptom (!)

-Removing xfce-power-manager with synaptic :

Normal service restored. Laptop lid now correctly suspends and log-off results in the welcome login page.

@Thaddäus

!! CORRECTION !!

On trying again. Lid close provokes black screen. NOT solved after all

Did you remove the "upower" package also?

@Damien:

"Simply logging off provokes the back screen symptom (!)"

So your issue occurs at the login screen and not after logging in? If this is the case, it has nothing to do with xfce4-power-manager.

@Thaddäus

same behaviour if upower is removed or not, Same behaviour is xfce-power-manager is removed or not, EXCEPT that the first time the laptop lid is closed after reboot OR logoff expressly invoked, all works well. After that, the same behaviour is seen.

@Sean

The laptop only sees the login screen after a logoff. The system is set to auto-logon.

A reminder that this all worked perfectly with 12.04 LTS from first install right up to the latest 12.04.4 LTS updates. The problem only started on a new install of 14.04.1 LTS as reported above. The installation is absolutely standard.

Further comment :

The black screen seen on logout is DIFFERENT to the black screen problem on lid close.

Logout will allow a smooth power down on power switch press. Terminal reports normal activity. This could be the backlight issue reported elsewhere?

On lid close the only recourse is forced power down. Often there is a frozen mouse cursor visible.

I was having the same issue, the original fix didn't work for me on my Lenovo Thinkpad E520.

After following posts #7 and #16 by Barnabas issue is resolved.

As you indicated, no combination of settings seems to help, and you'll probably continue to see a similar issue without xfce - power - manager or light-locker. This seems like it is an issue with X or the kernel. For your sanity, try setting logind-handle-lid-switch to true (default), uninstall light-locker, install xscreensaver, and reboot.

Unsure if my problem is related or not. I have observed in a few occasion today where I see the light-locker login. After login I get a black screen. This only happens /sometimes/ not sure how to reproduce it.

I've followed the instructions to fix the previous problem regarding the same symptom with xfce4-power-manager. I did see that my setting is:

/xfce4-power-manager/lock-screen-suspend-hibernate false
/xfce4-power-manager/logind-handle-lid-switch true

which I'm not sure if it contributed to this issue, but I've set it to the other way around and observing the outcome within the next few days.

Damian, this report might be a duplicate of bug 1254131 (Dell Latitude D505).

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v3.17 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

If you are unable to test the mainline kernel, for example it will not boot, please add the tag: 'kernel-unable-to-test-upstream'.
Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.17-rc5-utopic/

@Thaddaus,

Yes I agree. Bug #1254131 shows the same symptoms. Combine?

This bug is affecting me also. When using the regular Ubuntu distro though, it works just fine, it only affects me when I use Xubuntu.

To add to this also happening to me, I do see the lock screen when I open my laptop, and it's only then when I enter my password does the screen go black.

This is the same bug that is reported here: https://bugs.launchpad.net/bugs/1283938

For me this is present also on ubuntu 14.10, kubuntu 14.04 and with the kernel 3.17 rc6.

It seems like the bug is back with 14.10. Entering password works, after password is entered, the screen is locked.

My work around of binding an xrandr call to a hotkey still works for this.

I had the same symptoms with my Samsung NP300E4X notebook and like Matt I found that post #7 and post #16 solved it.

For all those who have no success stopping the suspend by editing /etc/systemd/logind.conf or found that rm ~/.config/xfce4/xfconf/xfce-perchannel-xml/xfce4-power-manager.xml only works temporarily, I had success using gksudo gedit /etc/UPower/UPower.conf and then setting IgnoreLid=true.

A second work around is to hit ctrl+alt+f1, sign in using your username(lower-case) and password, then enter sudo restart lightdm, followed by your password again (some times this has to be done all with a pitch black screen)

Not ideal I know but is the best solution i've found.

#7 and #16 didnt work for me :(

This also seems to affect Ubuntu 14.04.1 AMD64. I had this exact issue and when I came back from a reboot it gave me an Apport report, something about vbetool failing with SIGSEV().

I am also experiencing this bug with Ubuntu 14.04.1 AMD64 on an HP Stream 14 Chromebook. Surprise was that I was previously running 14.04 on this laptop via crouton and it worked a dream, so I did not expect any issues at all in upgrading to the LTS version.

However, the upgrade has been a very painful experience compared to the 14.04 distro. My touchpad stopped working, which I was able to resolve by upgrading the kernel to 3.17. But, I am still unable to get past this issue with suspend.

I have disabled suspend/hibernate for now, but this means i have to keep my laptop constantly plugged in when I am not using it or it will run out of battery. As you can imagine, this is annoying for any laptop user and even more annoying when this feature worked fine on the non LTS release. Please let me know if i can provide more information for debugging.

With a default xubuntu 14.10 install on 2 different laptops (MacBook Air 4,1 and HP folio 9470m) I can reproduce this issue. For me the black screen occurs after login.

Adjusting power management settings has not yet helped. I did find that I can solve the problem by reclosing the lid, waiting for suspend and opening it again. The 2nd time seems to work as expected.

After trying unsuccessfully to use all the fixes I found online, I finally managed it to fix this problem myself today:

1. Install Gnome Screensaver
    sudo apt-get install gnome-screensaver
2. Replace Light Locker with Gnome Screen Saver
    Do it first for all new users
    sudo vi /etc/xdg/autostart/light-locker.desktop
    Change the line from:
         Exec=light-locker
     to:
         Exec=gnome-screensaver
   and then do the same for every existing user
   su <username>
   vi ~/.config/autostart/light-locker.desktop
3. Hide light-locker-settings from menu for all users
   sudo vi /usr/share/applications/light-locker-settings.desktop
   Add the line:
   Hidden=true

Hope that helps everyone affected by his bug until Light Locker is actually production ready enough to warrant it's place in a LTS release.

I believe this is more than just an xubuntu issue or a laptop one in 14.04. I run a desktop with stock ubuntu and unity, 12.04.4 fully upated via the repositories with no foreign drivers for the graphics. ie nouveau as supplied in the original install and updated only via normal updates if nouveau has ever been updated in 12.04. The graphics card is Nvidia at least 3 years old and certainly not one of the esoteric ones, probably close to the bottom of the nvidia range. Suspend resume works perfectly.
On setting up 14.04 for testing on the same hardware with the exception that 14.04 is on an hd whereas 12.04 is on an ssd, it would not resume with the keyboard and mouse hanging alternatively and never being able to get back to an operating desktop. I went as far as doing a suspend from a real terminal using pm-suspend. I could revert to the terminal but still not the desktop. My rudimentary testing indicates its a nouveau driver issue. I tried the 12.04 kernel on the 14.04 but to no effect. I installed the nvidia binary and hey presto suspend resume works. As Linus says nouveau driver taints the kernel!! At the moment the relevant desktop is out of action but a I can resurrect it should you require some log/error report dumps as specified by you.

I'd just like to confirm this bug on a (nearly) fresh install of Xubuntu 14.04 32bit. Installed on an HP Mini with a 32gb SSD with the problem evident, and I moved the SSD to my HP Pavilion dv6 and the problem persists.
After trying a few of the above fixes (except for gnome-screensaver) the issue still plagues both machines. I hope this gets resolved soon! :(

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]

I downgraded from xubuntu 15 to 12 on a Sony Vaio and not only does the wake up after suspend work, the system is faster too. I will stick with v12 and disable the updates.

Still busted. Guys...this is on 15.10, some 18 months past the time that you honestly found this to be a problem and largely should've found the blasted thing.

Desktops, servers, and phones aren't and shouldn't be your sole focus. FIX THIS. I don't care who, upstream, you have to dopeslap to do this, but it's a noxious combination of logind (it screws up on a second login, guys...there's a hint...) LightDM, and Lightlocker.

Now, for reference...

MSI Apache Pro GE72-2QE.

i7-5700hq
16Gb of DDR3
NVidia GTX960m

Nothing that isn't supported, either with a bit of telling nouveau to not do modesetting, or the like. I should be able to, once I get Bumblebee/Optimus/Primus running, have a beast of a laptop that doesn't have suspend or similar problems. Furious about this not being fixed by now doesn't begin to describe this, guys.

This persists for me as well. Is there any hope this will be fixed in 16.04?

I'm experiencing this problem on Xubuntu 16.04 :[

This solution works on my laptop (ubuntu 16.04, but should work on previous OS):
open as root file
/etc/UPower/UPower.conf
and change IgnoreLid=false ==> IgnoreLid=true
save changes, restart system and now it works :-)
You can remove light-locker now.

You can use bash for these:
sudo sed -i -e 's/IgnoreLid=false/IgnoreLid=true/g' /etc/UPower/UPower.conf
sudo apt-get remove --purge -y light-locker light-locker-settings

Unfortunately no change on 14.10.

Only workaround remains a very inconvenient suspend through menu.

________________________________
From: <email address hidden> <email address hidden> on behalf of Piotr Admin <email address hidden>
Sent: 09 July 2016 21:30
To: <email address hidden>
Subject: [Bug 1357090] Re: Black screen on resume in Xubuntu 14.04.1

This solution works on my laptop (ubuntu 16.04, but should work on previous OS):
open as root file
/etc/UPower/UPower.conf
and change IgnoreLid=false ==> IgnoreLid=true
save changes, restart system and now it works :-)
You can remove light-locker now.

You can use bash for these:
sudo sed -i -e 's/IgnoreLid=false/IgnoreLid=true/g' /etc/UPower/UPower.conf
sudo apt-get remove --purge -y light-locker light-locker-settings

--
You received this bug notification because you are subscribed to the bug
report.
https://bugs.launchpad.net/bugs/1357090
Bug #1357090 "Black screen on resume in Xubuntu 14.04.1 ...<https://bugs.launchpad.net/bugs/1357090>
bugs.launchpad.net
I have had this problem as well when locking the screen on suspend/lid close with Xubuntu 14.04.1 (with all updates applied) while using light-locker for the lock screen.

Title:
  Black screen on resume in Xubuntu 14.04.1

Status in linux package in Ubuntu:
  Expired

Bug description:
  It seems #1303736 is Not fixed.

  Black screen on resume when using standby on close lid is confirmed on
  Dell Latitude D400 on completely new install of Xubuntu 14.04.1 32
  bit. downloaded 14 Aug from repository as a .ISO image.

  This despite claims to the contrary on the website.
  http://xubuntu.org/news/xubuntu-14-04-1-released/ pointing to
  https://bugs.launchpad.net/ubuntu/+source/xubuntu-default-
  settings/+bug/1303736

  Using the "Suspend" key results in correct operation, i.e. the laptop
  suspends and resumes correctly on lid open. Suspending by closing the
  laptop lid results in the black screen when re-opening. Once in black
  screen mode, the only recourse is power off re-boot.

  Although power manager is set correctly to "Suspend" in the power
  manager , on closing the lid the system does NOT appear to suspend as
  it does when the "Log-off Suspend" button is clicked or the hardware
  "Suspend" key is pressed i.e. the problem APPEARS to be on lid close.

  Power manager and light-locker set NOT to lock on suspend or shutdown
  makes no difference to behaviour.

  Xubuntu up to 12.04.4 (plus latest updates) worked absolutely
  correctly before new install of 14.04.1

  This is a MAJOR inconvenience for an upgrade of an LTS.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1357090/+subscriptions

#60 and #51 solved my issue. Kudos to them

#51:

After trying unsuccessfully to use all the fixes I found online, I finally managed it to fix this problem myself today:

1. Install Gnome Screensaver
    sudo apt-get install gnome-screensaver
2. Replace Light Locker with Gnome Screen Saver
    Do it first for all new users
    sudo vi /etc/xdg/autostart/light-locker.desktop
    Change the line from:
         Exec=light-locker
     to:
         Exec=gnome-screensaver
   and then do the same for every existing user
   su <username>
   vi ~/.config/autostart/light-locker.desktop
3. Hide light-locker-settings from menu for all users
   sudo vi /usr/share/applications/light-locker-settings.desktop
   Add the line:
   Hidden=true

Hope that helps everyone affected by his bug until Light Locker is actually production ready enough to warrant it's place in a LTS release.

#60:

This solution works on my laptop (ubuntu 16.04, but should work on previous OS):
open as root file
/etc/UPower/UPower.conf
and change IgnoreLid=false ==> IgnoreLid=true
save changes, restart system and now it works :-)
You can remove light-locker now.

You can use bash for these:
sudo sed -i -e 's/IgnoreLid=false/IgnoreLid=true/g' /etc/UPower/UPower.conf
sudo apt-get remove --purge -y light-locker light-locker-settings