Desktop: Black screen after logging into unity8 session

[Daniel Holbach]

On xenial amd64 desktop after logging into the unity8 session, I'm greeted by a black screen, no mouse cursor, nothing. Only Magic SysRq gets me out of the session.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: unity8 8.11+16.04.20160129-0ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-2.16-generic 4.4.0
Uname: Linux 4.4.0-2-generic x86_64
ApportVersion: 2.19.4-0ubuntu2
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Feb 8 15:07:17 2016
InstallationDate: Installed on 2015-04-30 (283 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
SourcePackage: unity8
SystemImageInfo: Error: command ['system-image-cli', '-i'] failed with exit code 2:
UpgradeStatus: No upgrade log present (probably fresh install)

[Albert Astals Cid (aacid)]

Can you check if you're hitting https://bugs.launchpad.net/canonical-devices-system-image/+bug/1525285 ?

login into the same user on a X11 session and run gst-inspect-1.0 and then try logging back under unity8

[Daniel Holbach (dholbach)]

No, that doesn't seem to be the issue.

[Stephen M. Webb (bregma)]

Possibly https://bugs.launchpad.net/mir/+bug/1526658?

[stinger (dev-t)]

Possibly https://bugs.launchpad.net/bugs/1542939 if you have a i915 gpu ?

[Daniel van Vugt (vanvugt)]

First try this:
sudo apt-get remove mir-client-platform-mesa3 mir-client-platform-mesa2 mir-client-platform-mesa1
and reboot. If that fixes it then it's bug 1526658.

Second wait a full minute on the black screen. If it gives up and returns to to a (broken) login screen after 30 seconds then it's bug 1536662.

[Daniel Holbach (dholbach)]

It's not bug 1526658 and not bug 1536662.

I moved the files in /var/log/lightdm and .cache/upstart somewhere else and after logging in the screen doesn't stay black, but after some quick flickering I'm back to the lightdm screen. I have to restart lightdm before I can even log back into the regular unity7 session. No crash files available.

[Daniel Holbach (dholbach)]

()
qtmir.screens: ScreenController::ScreenController
[1455004145.996445] mirplatform: Found graphics driver: mir:mesa-kms (version 0.19.1)
[1455004146.000172] mirplatform: Found graphics driver: mir:mesa-x11 (version 0.19.1)
[1455004146.000454] mirplatform: Found graphics driver: throw-on-creation (version 0.19.1)
[1455004146.000508] mirplatform: Found graphics driver: dummy (version 0.19.1)
qtmir.mir: MirServer created
[1455004146.002313] mirserver: Starting
ERROR: QMirServer - Mir failed to start

----------

Loading module: 'libubuntu_application_api_desktop_mirclient.so.3.0.0'
UbuntuClientIntegration: connection to Mir server failed. Check that a Mir server is
running, and the correct socket is being used and is accessible. The shell may have
rejected the incoming connection, so check its log file

[Daniel van Vugt (vanvugt)]

How about /var/log/lightdm/unity-system-compositor.log ?

You will get some nice detailed log info from Mir there.

[Daniel van Vugt (vanvugt)]

BTW bug bug 1536662 is really hard to work around. I've been trying today and still failed most attempts...

And /var/log/lightdm/unity-system-compositor.log will also tell for certain if that bug is a factor.

[Daniel van Vugt (vanvugt)]

Hmm, I can't explain that right now. Although I have seen new and exciting crashes in peoples' unity8.log recently (and mine right now). Do you see any crashes or "ERROR" in your unity8.log?

[Daniel Holbach (dholbach)]

daniel@daydream:~$ grep ERROR .cache/upstart/unity8*
daniel@daydream:~$

[Daniel van Vugt (vanvugt)]

Sorry, can you check for "exception" or "corruption" in unity8.log? I've been seeing both recently...

[Daniel Holbach (dholbach)]

daniel@daydream:~/.cache/upstart$ zgrep -ie "(exce|corru)ption" *
daniel@daydream:~/.cache/upstart$ cd /var/log/lightdm/
daniel@daydream:/var/log/lightdm$ sudo zgrep -ie "(exce|corru)ption" *
daniel@daydream:/var/log/lightdm$

[Daniel van Vugt (vanvugt)]

In another recent bug someone else is reporting similar start-up failures. In that case they found it started working reliably with Mir 0.20.0 and later. Although the fix if any could have come from Mesa or somewhere else.

Daniel: Are you still having problems since we released Mir 0.20 ?

[kevin gunn (kgunn72)]

@dholbach - can you try again with an updated mir?
we're on Mir 0.20.3 now...about to be on Mir 0.21

[Daniel Holbach (dholbach)]

It works for me now. The problem I'm seeing now is that the greeter does not use the German keyboard, but maybe I'm supposed to change the setting somewhere? In any case I think that's a separate bug.

[Daniel van Vugt (vanvugt)]

The only remaining black screen bug I know of for sure is bug 1536662. But there may be others...