Log in not available after lock screen with multi-monitor

What happens if you move the mouse on the external monitor?
Does the login prompt appear?
Or, are you able to just type (without seeing anything) and hit enter to get in?

The blank screen thing doesn't seem an unity issue, though. Since if you can see the ubuntu logo on the laptop screen, then it means that unity is not blanking the screen anymore, but it looks like that a lower level component (unity-settings-daemon's power module?) didn't turn that monitor on.

I can't get the mouse over to the external monitor. I can move it around in the laptop screen, but can't escape the boundaries of that screen when this is happening.

I tried typing the password (without being able to see anything), but that didn't work.

One more check to figure out where the problem might be:
 - Ctrl + Alt + F1
 - Login there and run:
     COMPIZ_CONFIG_PROFILE=ubuntu DISPLAY=:0 compiz --replace

At this point, go back with Ctrl+Alt+F7, and there unity should reload. If it resumes your session properly then it seems an unity's fault.

You can also just run "unity" from tty1, but that will relock your session. If compiz doesn't seem to reload try with a "killall -9 compiz" before.

PS: if you want to lower the idle delay needed to blank and lock the screen for testing purposes you can use
  gsettings set org.gnome.desktop.session idle-delay 1 # means 1 second

Use this to reset the default values instead:
  gsettings reset org.gnome.desktop.session idle-delay

Thanks Marco. I'm on the road for the next 10 days - will try this and give fedback when I'm back at my desk.

Hi Marco. I tried the steps from comment #3, but no luck. After Ctrl + Alt + F1 I can see the login prompt, but am not able to login as neither the laptop keyboard nor an external keyboard seem to be recognised (nothing happens - no letters, no error, no feedback). And since the keyboard isn't recognised, I can't even Ctrl + Alt + F7 to get back to Unity.

This is really strange... Because it's weird that the keyboard works once to go to tty1 and then it stops to send events...

Anyway I would say at this point that unity doesn't seem to be the guilty here.
Just another way, to make sure this is the case, enable the OSK (this would fallback to the old gnome-screensaver):
  gsettings set org.gnome.desktop.a11y.applications screen-keyboard-enabled true

Then give it another try, if you still get this problem, this is definitely not an unity issue.

Use this command to reset the on-screen-keyboard setting afterwards
  gsettings reset org.gnome.desktop.a11y.applications screen-keyboard-enabled

Marco - if you don't think it's unity, can you reassign to wherever you think is more appropriate? Thanks

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 1315369

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

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Can you get the syslog while booting with drm.debug=6 added to the kernel command line? That should get more information about the modeset failure.

Hi Maarten - happy to do that, but I need more explicit instructions.

Also, I've now seen this happen twice under slightly different circumstances. When I first reported this, I was referring to a situation in which my screen automatically locks after inactivity. To avoid that, I have now changed it so that it doesn't lock, but it does turn off after inactivity and am getting the same behaviour (i.e,. external monitor black, can't do anything on laptop, unplugging monitor makes both go black). I've now had to change to neither lock nor turn off after inactivity in order to maintain a functional system, but obviously this isn't an ideal config.

ok, press e during boot in grub, you'll see a line with 'linux /boot/vmlinuz-*', add drm.debug=6 to the end, then boot normally with ctrl-x or f10 and force the bad things to happen. attach the resulting /var/log/dmesg to the bug :)

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

To be explicit. We would like to obtain a system log with graphics debugging enabled, after reproducing the problem. We believe the following steps should achieve that:

1) reboot, interrupt grub, and add "drm.debug=6" to the kernel command line. There is a good guide on how to do this at the URL below, see the section "Temporarily Add a Kernel Boot Parameter for Testing":

   https://wiki.ubuntu.com/Kernel/KernelBootParameters

2) reproduce the issue

3) hit ctrl-alt-F1 to get the text login, and then hit the power button which should trigger a clean reboot.

4) boot normally, login and attach the files /var/log/dmesg, /var/log/dmesg.0 and /var/log/syslog.

Hope that makes sense.

Weirdly, this isn't happening as reliably as it used to. It still happens, but not 100% of the time, so I've hard trouble capturing it. I've applied some updates since I first reported it, so that may be changing the behaviour somewhat. I'm definitely still seeing it - just not every time.

And I'm seeing new things too. The dmesg.0 and syslog file I'm attaching today were captured after a similar issue (but not exactly the same). After the screen dimmed and locked, when I moved the mouse the monitor was blacked out and laptop screen on (as originally reported) but this time the login screen was on the laptop. However, I still couldn't log into it - no keyboard actions recognised, except ctrl-alt-F1 which blacked out the screen (but no console log in). I then had no option but to press power button.

I'll continue to try to capture logs with the orig symptoms, but hopefully these will help too.

Seems to be a bug in intel modesetting alright, I'll contact the intel graphics devs and see if they can do anything with it.

It's not related to Intel, I didn't have an Intel card. I have both an AMD and a Nvidia card, and this bug happens with both of them. I can't do an "apport-collect" as this bug is closed, please re-open it.

It's really annoying.

I would just like to chime in that unlike silbs, this has become more frequent for me. I have already rebooted my machine three times today.

Today I turned off allowing my machine to automatically lock or turn off the screen. Hopefully that will stave off the problem until a fix is issued.

Gregory and David, in order to make sure weather your problem is related to unity or not, please follow the steps I wrote above to double check.

Thanks.

I've had to stop using my external monitor completely to avoid the problem. I tried turning off screen locking and screen dimming to avoid it, but that didn't help. The only thing I have found that leaves me in a reliable working state is to not use the external monitor.

In my setup I have two monitor plugged into my laptop's base station. The graphics card will not support three monitors, so I only have the two external monitors activated. When I came in this morning the computer did not auto-lock or turn off the monitors and all was fine.

@3v1n0: There are many steps, do you mean the kernel arguments at grub? I will enter those the next time I reboot.

I meant to add that my symptoms are 100% exactly like silbs, except that my left monitor exhibits the behavior of her external monitor and my right monitor exhibits the behavior of her laptop's screen.

Could you please attach your /var/log/Xorg.0.log?

Added.

I added the kernel options and turned back on locking and turning off the monitor. Hopefully when I come back from lunch the problem will show. If so I will upload a new Xorg.0.log file.

Thanks.

Could you please test with a different kernel? It would help us to verify if there is already a patch for this issue available.

If possible test with our development branch drm-intel-nightly from http://cgit.freedesktop.org/drm-intel/log/?h=drm-intel-nightly

I have a 4-monitor set up and idling out to the lock screen seems to black screen freeze it about 25% of the time since 14.04 update. I'm able to restart lightdm via SSH in order to bring the screen back, but I still have to logout in order to get full access to all 4 monitors again after it happens.

I've attached my Xorg log

I'll try to run through the debugging a little bit later to attach the dmesg and syslog

@rodrigo-vivi-y: Can you point me to instructions on what to do to boot from a nightly kernel?

David: No I meant the ones I've pointed out in the previous comments... #6 and #3 in particular.

Here is my xorg logs during a crash while using the drm.debug=6 kernel option.

Here is the dmesg log.

This looks like a similar bug report: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1324935
There is a workaround identified here as adding the following to the kernel cmdline: linemodeset=0 video.allow_duplicates=1
In addition it seems like v3.9 and older kernels could potentially work meaning this could be a regression.

I tried the drm-intel-nightly kernel (from 18 June) and still experience the same problems as originally reported. I followed the steps in comment #31 to attach logs - those logs attached. The failure with these logs was slightly different though - behaviour was that I could see the login prompt, but no keyboard input was recognised - i.e., the same thing that I saw in comment #32. So sometimes failure is that I can't get to a screen with the login prompt and sometimes the failure is that the login prompt is there but I can't actually log in because keyboard input not recognised/processed.

I also tried the suggested workaround from comment #50 (with the Trusty kernel) and ran into the same problem. This time after screen locked, I had black external monitor, working laptop screen but without the login prompt, and no recognised keyboard input - I.e,. I couldn't event ctrl-alt-F1 to get to login prompt. I'll attach the logs below just in case they help.

Jane, could you please file a bug on bugs.freedesktop.org with this -nightly information?
There we definitely have a bug. That is similar/duplicated of 1324935 as Chris pointed out

Would you please try this branch http://cgit.freedesktop.org/~pzanoni/linux/?h=bdw-pc8-fixes , Intel QA has verified an issue (which we think is same as this one) on this appointed branch.

I switched from a VGA to an HDMI cable. I have not encountered the problem again since that switch.

I had this problem when I came back from lunch today. I am running a desktop with two DisplayPort monitors. I was able to move the cursor from monitor to monitor but no prompt appeared to allow me to enter my password. I had to go into a text console to reboot. I had a VM running which got aborted so this is very annoying.

This bug is still present for me with a fresh install of xenial.
I have a dual-monitor setting with DVI and HDMI.

As noted before, the behaviour is erratic, it does not happen every day or after each locked screen.
I am mostly unable to log in (unresponsive log-in screen or black screen) after relatively long periods of inactivity such as when I come back to the office in the morning.