Ubuntu 16.04 - Unity desktop session broken when using non-LightDM as X Display Manager

Bug #1569357 reported by 林博仁 on 2016-04-12
68
This bug affects 14 people
Affects Status Importance Assigned to Milestone
lxdm (Ubuntu)
Medium
Unassigned
sddm (Ubuntu)
Medium
Unassigned

Bug Description

As title, you'll only see your desktop file icons, no launcher and title/indicator bar are displayed.

You can only reproduce this issue when you choose non-LightDM DMs as well as the default X display manager

* SDDM: reproduced
* GDM3: not even launch-able on my system so can't verify
* LXDM: reproduced

This issue doesn't exist in Ubuntu 15.10, only in 16.04

## Workaround ##
* Switch to LightDM

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: sddm 0.13.0-1ubuntu5
Uname: Linux 4.5.0-buo-ren-vanilla-intel-ivybridge-optimized x86_64
ApportVersion: 2.20.1-0ubuntu1
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Apr 12 20:17:23 2016
InstallationDate: Installed on 2016-01-07 (95 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
SourcePackage: sddm
UpgradeStatus: Upgraded to xenial on 2016-04-07 (4 days ago)

林博仁 (buo-ren-lin) wrote :
Launchpad Janitor (janitor) wrote :

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

Changed in sddm (Ubuntu):
status: New → Confirmed
Changed in sddm (Ubuntu):
importance: Undecided → Medium
林博仁 (buo-ren-lin) on 2016-04-19
summary: - Ubuntu 16.04 - Unity DE not working properly when using SDDM to login
+ Ubuntu 16.04 - Unity DE broken when using SDDM to login
Patola (patola) wrote :
林博仁 (buo-ren-lin) on 2016-04-24
description: updated
Torbjörn Lönnemark (tobbez) wrote :

No, that linked issue seems to be another problem.

For this bug's issue, manually starting Unity as specified in the linked question works, while it doesn't for the person asking there (Unity crashes with an Illegal instruction).

On a side note the the desktop context menu works.

MAWSpitau (marcel-spitau) wrote :

Same problem here. I would like to use unity, but lightdm starts in a low grafics mode... Only sddm ist able to start the computer, but not unity. Which files, logs or what ever do you need?

林博仁 (buo-ren-lin) on 2016-04-28
summary: - Ubuntu 16.04 - Unity DE broken when using SDDM to login
+ Ubuntu 16.04 - Unity DE broken when using non-LightDM as X Display
+ Manager
description: updated
林博仁 (buo-ren-lin) wrote :

UPDATE: also reproducible on LXDM. I've mark all possibly relevant packages.

summary: - Ubuntu 16.04 - Unity DE broken when using non-LightDM as X Display
- Manager
+ Ubuntu 16.04 - Unity desktop session broken when using non-LightDM as X
+ Display Manager
description: updated
Kanwar Singh (kssgill) wrote :

sddm to unity broken. This temporarily gets me working:

right click and open shell
run

setsid unity

gets me back working in unity.

Sebastien Bacher (seb128) wrote :

that looks similar to bug #1293629, are those settings the XDG_CURRENT_DESKTOP env variable?

no longer affects: lightdm (Ubuntu)
no longer affects: unity (Ubuntu)
no longer affects: gnome-session (Ubuntu)
MAWSpitau (marcel-spitau) wrote :

In my case:

% echo $XDG_CURRENT_DESKTOP
Unity

林博仁 (buo-ren-lin) on 2016-05-13
description: updated
description: updated
Launchpad Janitor (janitor) wrote :

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

Changed in lxdm (Ubuntu):
status: New → Confirmed

For the people like me who have trouble finding how to switch to lightdm:

    sudo dpkg-reconfigure lightdm

but also remember to:

    sudo systemctl enable lightdm.service

You also might have to install lightdm before either of these if you didn't have it installed previously:

    sudo apt install lightdm

Afterwards, reboot.

Changed in lxdm (Ubuntu):
importance: Undecided → Medium
Nathan Adams (nadams) wrote :

Alejandro's instructions did not restore Unity for me.

But to make the process easier for those that want to try, here they are in an easy to copy & paste format:

sudo apt install lightdm
sudo dpkg-reconfigure lightdm
sudo systemctl enable lightdm.service
sudo reboot

Nathan Adams (nadams) wrote :

I am not entirely sure what corrected the problem, but here are all of the steps I performed:

sudo apt-get install lightdm
sudo dpkg-reconfigure lightdm
sudo systemctl enable lightdm.service
sudo reboot

rm -rf .cache/compizconfig-1
rm -rf .compiz
rm -rf .Xauthority
rm -rf .config/autostart
dconf reset -f /org/compiz
setsid unity

At this point, Unity sprang to life for me.

Robert Phair (rphair) wrote :

I am also unhappy to confirm this problem but happy to find that this is a corroborated bug. As the OP reports, "gdm3" hangs the system before the Unity desktop comes up, and trying to use "sddm" starts an X session without any window management.

Jim Hargrove (jhargrove) wrote :

Megathanks to Nathan Adams for post #14 on this page. My Unity desktop had been functioning perfectly since upgrading to 16.04 nearly 10 months ago, but it suddenly broke yesterday for no reason I can fathom. (Last system action I had performed was to enable the system firewall - ufw.) I tried uninstalling and reinstalling Unity and LightDM, but neither action solved the problem

Then I entered each of Nathan's 10 lines above in a terminal, and when the last line executed, Unity sprang back to life. Thanks, Nathan!

I had all things done, lightdm installed, removed dotfiles, but didn't work. If I run lightdm as root, it starts and allows me to login.

Only the following command fixes it, which sets the lightdm as the default display manager. But I wanted to used sddm instead, because it works better with my non-functional laptop display.

    sudo dpkg-reconfigure lighdm

and selecting lightdm as the default.

tags: added: lxdm sddm

Not completely non-lightdm, Unity session can be started using gdm3. Only sddm has problem starting either GNOME3 or Unity session

Igor (cryptor1) wrote :

@nadams
The only steps I've performed from your list to fix the issue are:

rm --recursive ~/.cache/compizconfig-1
rm --recursive ~/.Xauthority
dconf reset -f /org/compiz
setsid unity

I don't think there is a need to remove ~/.config/autostart directory

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