12.04 black screen with blinking cursor when switching users

[Noel Arzola]

When switching users on 12.04 it will sometimes just go to a black screen with a cursor. The user switching to is not logged in yet.

Expected behavior:
Click current user up top> from the drop-down click the user wanting to log in > brought to the lightdm log in screen and log that user in

Instead:
Click current user up top> from the dropdown click the user wanting to log in > brought to a black screen with a blinking cursor

From here, you cannot type or initiate any keyboard shortcuts other than Ctrl +Alt+F(1-6) to reach tty1 etc, or Ctrl+Alt+F7 to return to the user that you were originally trying to switch from. Ctrl+Alt+F8 will bring you back to the black screen.

This happens pretty often so I should be able to test anything needed. Thanks!

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: lightdm 1.2.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-24.37-generic 3.2.14
Uname: Linux 3.2.0-24-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.0.1-0ubuntu7
Architecture: amd64
Date: Fri May 18 08:00:55 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)

[Noel Arzola (noel.arzola)]

Oh, if you log the current user out instead of switching it will bring you to the log in screen without issue

[Sebastien Bacher (seb128)]

Thank you for your bug report, could you add your /var/log/lightdm/lightdm.log after getting the issue?

[Sebastien Bacher (seb128)]

Do you have also steps to trigger it? Do you change vt with the keyboard sometimes (i.e ctrl-alt-f<n>)

[Noel Arzola (noel.arzola)]

Sorry, the steps above under "instead" are the reproduction steps, we strictly switch through the indicator/lightdm process. I only mentioned the keyboard shortcuts to advise what could be done from the blank screen once it appears. Will work on getting that file up

[Sebastien Bacher (seb128)]

How many users do you have logged in? It would help to have steps on changes, logout actions ... like does it happen only after you logged out from some accounts? Or does it happen with 2 accounts and changing between those?

[Noel Arzola (noel.arzola)]

Gotcha. 2 users on the machine, me and my wife. Her account (michelle) is set to auto-login on boot. This only appears to occur going from her account to mine. This happens with her logged in and mine logged out. Typically not on the first attempt. So she will be logged in, I will click to switch to mine, log in at the login screen, once I'm done I logout, she switches to her from the login screen to resume her session, then later when I again attempt to login using the steps above the screen comes up.

[Noel Arzola (noel.arzola)]

Anything in there that helps or anything I might be able to add or try out?

[Noel Arzola (noel.arzola)]

Fully updated, issue remains

[Launchpad Janitor (janitor)]

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

[Noel Arzola (noel.arzola)]

Pressing ctrl+alt+del when this happens reboots the system. Not sure why someone would want to do that though, it is much easier to hit ctrl+alt+f7 and will ensure nothing is corrupted or lost for the current user.

[Noel Arzola (noel.arzola)]

Anyone run into this on 12.10?

[Crick (crick)]

Additionally, when this happens sometimes my computer is unresponsive. None of the ctrl-alt-F* keys do anything, nor does ctrl-alt-del or for that matter any other key combination I try. The cursor still flashes though, so the computer itself did not freeze.

[Crick (crick)]

I also note that something similar used to happen in Hardy, though I can't recall whether the cursor would flash or not. Note that this doesn't happen every time either, usually only maybe after a few days to a couple weeks. But like one of the other people people here have said, the user will be switched from myself to my wife multiple times per day. So in almost every case, this bug only surfaces after quite a few user switches.

[Noel Arzola (noel.arzola)]

Crick would you be able to add your /var/log/lightdm/lightdm.log after getting the issue as well please?

[Crick (crick)]

No problem. After it happened this last time, I booted using a boot cd to copy the file, so the last entries you see will have happened right before I had to manually shut it down. Here it is. Logins changed to preserve anonymity.

[Crick (crick)]

Note that sometimes when I log in to an account that is already in use, it attempts to log in and then fails, indicating that the account is no longer logged in. However, you can then login as per normal, just that everything you had open is no longer open. Annoying, but it doesn't hang. This event will also be in that same lightdm log, as it happened earlier today.

[Mike Szmansky (mszmansky)]

This bug also affects me and my family all the time. Usually happens when my kids or wife try to switch users after I am logged in. When it happens, I can always hit alt+f7 to get back to my logged in shell but unless I actually log out, nobody else can use the computer. I am using 12.04.1 LTS

[Scott Pitcher (scottypitcher)]

We have the same problem here with 12.04. Usually my wife is affected when she wakes the PC up (from Sleep) after I was using it, and attempts to Start New Session, but ends up with a black screen and the cursor blinking in the top left corner. The problem has persisted through several updates. We are using 12.04.2 LTS

[Amr Ibrahim (amribrahim1987)]

I have this problem only after installing a clean Ubuntu 12.04.2. The new hardware stack (*-lts-quantal) is installed by default.

Here is a typical case to reproduce:

1) Only user A is logged in
2) Switch to user B via indicator (using HUD) -> Success
3) Switch back to user A via indicator (using HUD) -> Black screen

I don't experience this bug on the original Precise hardware stack.

[Amr Ibrahim (amribrahim1987)]

Similar bug https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/625760

[Alan Walter Thomas (alazyworkaholic)]

I'm still having this problem in 13.10.
Importance ought to be higher considering that a rather basic feature is broken & workarounds require restart/terminal fixes, no?

[J.C. Blouin (lejcdublouin)]

I've had the same problem for months on 12.04. I was considering an upgrade to address it. I'm disappointed to hear that this is still an issue in 13.10, and agree with A.W. Thomas that importance should be higher.

[Anthony (anthonyryanirl)]

I am also affected by this issue

Running 12.04 full updated.

Same scenario as above

Logged in as account 1 - autologin enabled
Switch to Account 2
- sometimes make it, sometimes get the black screen

Only resolution is CTRL+ALT+DEL (complete restart) or CTRL + ALT+F7 to go back to Account 1.

This problem has manifest itself in the last 24 hours, of which only three changes have occurred.
- Update of new h/w - was working after new CPU/Mobo/Ram installation
- Update of new VM's using Virtual Box - again was working
- Install of Synergy and configured between Ubuntu and Mac.
  - switching off Synergy has not resolved the issue.

The first time it happened I wasn't aware of CTRL+ALT+F7 so done a reboot. Issue was resolved for a while

Tail end of lightdm.log - note AnneMarie is Account 2. I notice that it spawns 26350 to switch, but that exists with a value of 1 and stops. No reasoning why

[+20862.79s] DEBUG: Switching to user annemarie
[+20862.79s] DEBUG: Starting new display for greeter with user annemarie selected
[+20862.79s] DEBUG: Starting local X display
[+20862.79s] DEBUG: Using VT 8
[+20862.79s] DEBUG: Logging to /var/log/lightdm/x-1.log
[+20862.79s] DEBUG: Writing X server authority to /var/run/lightdm/root/:1
[+20862.79s] DEBUG: Launching X Server
[+20862.79s] DEBUG: Launching process 26350: /usr/bin/X :1 -auth /var/run/lightdm/root/:1 -nolisten tcp vt8 -novtswitch
[+20862.79s] DEBUG: Waiting for ready signal from X server :1
[+20866.54s] DEBUG: Process 26350 exited with return value 1
[+20866.54s] DEBUG: X server stopped
[+20866.54s] DEBUG: Removing X server authority /var/run/lightdm/root/:1
[+20866.54s] DEBUG: Releasing VT 8
[+20866.54s] DEBUG: Display server stopped
[+20866.54s] DEBUG: Stopping display
[+20866.54s] DEBUG: Display stopped

[Anthony (anthonyryanirl)]

Also adding the output from the x-1.log which is referenced above

 cat x-1.log

X.Org X Server 1.11.3
Release Date: 2011-12-16
X Protocol Version 11, Revision 0
Build Operating System: Linux 2.6.42-37-generic x86_64 Ubuntu
Current Operating System: Linux blackbetty 3.2.0-58-generic #88-Ubuntu SMP Tue Dec 3 17:37:58 UTC 2013 x86_64
Kernel command line: BOOT_IMAGE=/vmlinuz-3.2.0-58-generic root=UUID=UUID-WOZ-ERE a ro quiet splash vt.handoff=7
Build Date: 16 October 2013 04:41:23PM
xorg-server 2:1.11.4-0ubuntu10.14 (For technical support please see http://www.ubuntu.com/support)
Current version of pixman: 0.24.4
 Before reporting problems, check http://wiki.x.org
 to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
 (++) from command line, (!!) notice, (II) informational,
 (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.1.log", Time: Sun Jan 5 21:20:04 2014
(==) Using config file: "/etc/X11/xorg.conf"
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:17:0) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:18:0) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:18:1) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:18:2) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:19:0) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:19:1) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:19:2) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:20:0) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:20:1) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:20:2) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:20:3) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:20:4) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@0:20:5) found
(WW) fglrx: No matching Device section for instance (BusID PCI:0@1:5:1) found

Fatal server error:
AddScreen/ScreenInit failed for driver 0

Please consult the The X.Org Foundation support
  at http://wiki.x.org
 for help.
Please also check the log file at "/var/log/Xorg.1.log" for additional information.

 ddxSigGiveUp: Closing log
Server terminated with error (1). Closing log file.

and finally since it mentions Xorg.1.log we see the following
[ 23042.975] (II) fglrx(0): Kernel Module Build Time Information:
[ 23042.975] (II) fglrx(0): Build-Kernel UTS_RELEASE: 3.2.0-58-generic
[ 23042.975] (II) fglrx(0): Build-Kernel MODVERSIONS: no
[ 23042.975] (II) fglrx(0): Build-Kernel __SMP__: yes
[ 23042.975] (II) fglrx(0): Build-Kernel PAGE_SIZE: 0x1000
[ 23042.975] (II) fglrx(0): [uki] register handle = 0x00004000
[ 23042.975] (EE) fglrx(0): Not enough video memory to allocate primary surface (frame buffer).
[ 23042.975] (II) fglrx(0): Shutdown CMMQS
[ 23043.062] (II) fglrx(0): [uki] removed 1 reserved context for kernel
[...

[Anthony (anthonyryanirl)]

this was mentioned here(http://forums.amd.com/game/messageview.cfm?catid=485&threadid=166361)

When locking the screen or switching users, I get a blank screen. The only way to resolve is to reload the fglrx module and restart GDM3

unfortunately I don't know nor have the instructions on how this was done

Any one have any ideas on this as a work around

[taj (othertaj)]

Problem still exists in 13.10 64-bit
lightdm version 1.8.4.0ubuntu1

Only restart of LightDM (sudo service lightdm restart) from a terminal (with Alt-F1) resolves the problem, but it also kills the running session.

Because this is such a long standing and basic bug (mind you: one only has to click the logged in user name and Switch User to run into it) I agree with J.C. Blouin that the importance should be higher.

[taj (othertaj)]

I have an ubuntu install on an external drive and with the same drive on another laptop the bug does not occur.
I.e. the bug is related to the hardware.
I get the blinking cursor bug on HP Probook 6470b
I can switch users without problems on HP Compaq NC6320

[Robert Ancell (robert-ancell)]

Closing assumed fixed.