setting an invalid greeter makes lightdm say that you are in low graphics mode

Reported by Matt Fischer on 2012-04-02
44
This bug affects 10 people
Affects Status Importance Assigned to Milestone
Light Display Manager
Low
Unassigned
xdiagnose
Undecided
Unassigned
lightdm (Ubuntu)
Undecided
Unassigned

Bug Description

In the process of experimenting with a new greeter, I mistyped the greeter name. When I did this and restarted lightdm, lightdm throws up a screen saying I'm in low graphics mode "Your screen, graphics card, and input device settings could not be detected correctly". At this point, none of the options provided works. I double checked my lightdm conf file and caught the error, but this is a confusing and incorrect message in this specific case.

See screen cap attached.

To repro, edit lightdm.conf and set "greeter-session=fred" or anything that's not a valid session name.

I'm running lightdm 1.1.9-0ubuntu1

Matt Fischer (mfisch) wrote :
Robert Ancell (robert-ancell) wrote :

Matt, you keep finding all the bugs we like to pretend don't exist :)

Yeah, we need a way of providing some information to failsafe X as to why lightdm didn't start. The solution to this will probably have to be failsafe X scanning the log files for some known regexps and using those to suggest to the user why the problem existed.

Changed in lightdm:
status: New → Triaged
importance: Undecided → Low
Matt Fischer (mfisch) wrote :

Couldn't lightdm check for the existence of the requested greeter and just bail when it's not present?

Robert Ancell (robert-ancell) wrote :

That's what it's done; failsafe X is started when lightdm exits with an error. It's the catch all for when you can't get a normal graphical display up.

Daniel (hackie) wrote :

In my case, the bad greeter-session setting appeared after removing unity. I also think the greeters themselves should do something like update-alternatives when they get uninstalled.
But more important is a better error message.

Bryce Harrington (bryce) wrote :

Yeah, parsing the lightdm logs is doable. Mind attaching an example log?

Also provide detailed steps to reproduce.

Bonus points if you can suggest a good wording for an error message.

Changed in xdiagnose:
status: New → Incomplete
Matt Fischer (mfisch) wrote :

Repro steps are in the original description:

"To repro, edit lightdm.conf and set "greeter-session=fred" or anything that's not a valid session name."

Logs are attached.

Matt Fischer (mfisch) wrote :
Mathias Dietrich (theghost) wrote :

If you installed and removed lightdm-kde-greeter and you want to go back to Unity's lightdm try:

    sudo dpkg-reconfigure unity-greeter
    sudo dpkg-reconfigure lightdm

and select lightdm and reboot.

Nathan Hartley (treestryder) wrote :

This happened to me while I was trying to remove that darned Guest Login option from the logon screen. Do you think I could argue, that the Guest Login triggered a denial of service attach against my PC and thus needs to be removed from the default install?

Thanks for this bug report. I had gone a long time without rebooting, when I finally applied updates and went to bed the night before I found the error. I never would have put the cause and effect together otherwise.

Matt Fischer (mfisch) wrote :

@Nathan: You could use /usr/lib/lightdm/lightdm-set-defaults next time, it's a safer way to change options.

piotr zimoch (ebytyes) on 2013-05-22
Changed in lightdm:
status: Triaged → New
status: New → Incomplete
status: Incomplete → Opinion
status: Opinion → Invalid
status: Invalid → Confirmed
status: Confirmed → In Progress
status: In Progress → Fix Committed
status: Fix Committed → Fix Released
Changed in xdiagnose:
status: Incomplete → New
status: New → Incomplete
status: Incomplete → Invalid
status: Invalid → In Progress
status: In Progress → Fix Committed
status: Fix Committed → Fix Released
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