Lightdm refuses to work after installing kubuntu-desktop

Bug #1473149 reported by KnightStalker
This bug affects 4 people
Affects Status Importance Assigned to Milestone
lightdm (Ubuntu)
Nominated for Vivid by Alberto Salvia Novella

Bug Description

After installing kubuntu-desktop meta package I saw a prompt telling me that both sddm and lightdm are available and I am forced to choose one between I chose lightdm.on the next reboot I was unable to use GUI.
After 2-3 weeks,I retried using sudo dpkg-reconfigure lightdm and selected lightdm.still fails to run GUI.
sddm works fine and is able to handle both Plasma and Unity.
Ubuntu 15.04 with lightdm 1.14.2-0ubuntu1

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: lightdm 1.14.2-0ubuntu1
ProcVersionSignature: Ubuntu 3.19.0-22.22-generic 3.19.8-ckt1
Uname: Linux 3.19.0-22-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
CurrentDesktop: KDE
Date: Thu Jul 9 21:15:22 2015
InstallationDate: Installed on 2015-06-09 (30 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)

Revision history for this message
KnightStalker (knightstalker123) wrote :
Revision history for this message
Robert Ancell (robert-ancell) wrote :

Your lightdm,.log shows that you are failing to authenticate:
[+83.70s] DEBUG: Session pid=1546: Authentication complete with return value 7: Authentication failure

So it appears that something in PAM is failing (or you are typing the wrong password!)

Revision history for this message
KnightStalker (knightstalker123) wrote :

Robert Ancell,Perhaps apport didn't generate good quality logs.I indeed enter wrong passwords a lot when I try to login.
but that is NOT the problem.It doesn't even get to login prompt when it fails the way I mentioned.It freezes on a black screen.and it doesn't show anything.after a small time I'll see the regular detailed start up screen.(The one you can see when Kubuntu/Ubuntu is starting up and you press Esc button to see)and then it freezes up,this time forever.(or is very slow?but sddm works instantly)
I do not know how to create better quality logs.

Revision history for this message
Robert Ancell (robert-ancell) wrote :

The log file is /var/log/lightdm/lightdm.log. If you can reproduce the problem and then copy that file that would be useful in debugging.

Revision history for this message
Launchpad Janitor (janitor) wrote :

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

Changed in lightdm (Ubuntu):
status: New → Confirmed
Changed in lightdm (Ubuntu):
importance: Undecided → Critical
Changed in lightdm (Ubuntu):
status: Confirmed → Triaged
Revision history for this message
Hibernator (psychotux) wrote :

Bug hit me with Ubuntu 15.10 Beta 2 and now again on today released 15.10.

What I did:
I attempted to apt install kubuntu-desktop on freshly installed system.

What happened:
apt-get failed showing :
Errors were encountered while processing:
kde-telepathy-minimal: Depends: telepathy-mission-control-5 (>= 1:5.12) but 1:5.16.3-1ubuntu4 is installed
Package system was _completely_ broken. No more software installations or removals possible. apt-get install -f had no effect.
See also thread on this German Ubuntu forum about the broken package system bug:

At next reboot the system hung displaying only an Oxygen mouse cursor, no login manager appeared. System was completely trashed, not even virtual consoles worked. See also this successor bug:

What I expected to happen:
A smooth installation of KDE.

What I suspect to be the error:
The KDE package apparently installed incompletely due the bad dependencies mentioned and left the system in a broken state.

What I expect to be done:
Hot Fix: Remove the offending package "kde-telepathy" from metapackage kubuntu-desktop_1.331_amd64.deb.

I made and uploaded a patched kubuntu-desktop_1.331_amd64.deb package file which does not contain kde-telepathy.
To install KDE without destroying your system, download the patched .deb and install it via dpkg -i

Revision history for this message
Ubuntu Foundations Team Bug Bot (crichton) wrote :

The attachment "Patched kubuntu-desktop_1.331_amd64.deb without the offending subpackage kde-telepathy" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

tags: added: patch
Revision history for this message
JNH (jordannh) wrote :

I was having the same issue. I discovered the issue when I found errors written to `/var/log/seat0-greeter.log`:

    Error writing X authority: Failed to open X authority /var/lib/lightdm/.Xauthority: No such file or directory

Indeed, I only had `/var/lib/lightdm-data`. Running the command

    mkdir /var/lib/lightdm

and rebooting fixed the issue for me.

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