View Full Version : [SOLVED] No GDM login screen after upgrading from F23 to F24

29th July 2016, 06:07 PM
This happened on a two-seat machine with seat0 on Intel graphics and seat1 on an nVidia card (Nouveau driver).

After the upgrade to F24 only seat1 showed a GDM login screen while seat0 only showed [text] startup messages in a graphics mode and didn't switch to a login screen.

The logs showed several X servers being started and terminated on both seats with no reason why they were terminated.

I could switch consoles on seat0. After switching to a text mode TTY I could log on there and launch a proper X session with the "startx" command.

What did not appear was a graphical GDM login on seat0.

First try of a workaround (found unstable later, just for documentation): Turning off Wayland by editing /etc/gdm/custom.conf


Second workaround (much better): Using LightDM instead of GDM:

# dnf install lightdm system-switch-displaymanager
# system-switch-displaymanger lightdm

To make it work properly for logind multiseat configurations (the mechanism I use; introduced to Fedora a few years ago), you have to add a file to the LightDM configuration.

Create a file /etc/lightdm/lightdm.conf.d/multiseat.conf with the following content:


restart your system

EDIT: Sorry, the first workaround did not yet work as expected. The post was premature. The workaround is not yet stable. Most times the login screen appears on seat0 only.
EDIT: Added the LightDM workaround

30th July 2016, 09:16 PM
At the risk of hijacking a thread ... I have this problem on a laptop. It will not give me a graphical login screen even though systemd is set to use "graphical.default". The systemd log even says that this configuration is reached.

The system does not have /etc/gdm directory, so there is no custom.conf file to edit.

I can login with my normal user account and run startx. From there everything works as it should.

Bill Gee

31st July 2016, 02:21 PM
The /etc/gdm directory is part of the gdm-3.20.1-3.f24 package.

If it is not installed I assume that you either work with a different desktop environment (not GNOME) or your GDM installation is really broken.

1st August 2016, 12:21 AM
Indeed, there is no package called "gdm" on the computer. And I am a KDE user. Two things occur to me ...

First, I DO have Gnome installed. It is required for a few of the applications I use. It is not my primary environment, but it is there.

Second - Why does that matter to the login screen? At that point the system is running X but no desktop environment. Not Gnome - not KDE - not XFCE or LXDE or Cinamon or ....

This laptop used to go to a graphics login screen. It stopped a few weeks before I upgraded it from F23 to F24. It is not my primary computer so I have put up with the annoyance for a few months.

Bill Gee

1st August 2016, 11:42 AM
> I am a KDE user.
Then KDM is probably your display manager, not GDM and your problem may be with KDM, to be solved elsewhere.

> I DO have Gnome installed.
That's fine. Having it installed doesn't mean it is used for login. The display manager is responsible for graphical logins. You can even have more than one installed.

> Why does that matter to the login screen?
I think it doesn't matter. In F24, the link /etc/systemd/system/display-manager.service defines which display manager is active. I'm quite confident that it doesn't point to GDM. If so, the presence of GDM or GNOME on your system doesn't matter for getting a login screen.

> At that point the system is running X ...
Sure? As far as I see, the display manager (which doesn't seem to work on your box) starts up the X11 (or Wayland) servers. Even a graphical screen may come from Plymouth or so via a kind of plain frame buffer and doesn't need to be X based.

> ... but no desktop environment.
Probably not. It will come up with whatever it needs it, if it needs it. The display manager, the user session (the shell or window manager; started by the display manager, startx, etc.), or even a single application (that's why you have GNOME installed).

> This laptop used to go to a graphics login screen. It stopped a few weeks before I upgraded it from F23 to F24.
So things broke before the upgrade. I recommend looking at your KDM installation. Your issue is clearly not related to mine.

Good luck!

2nd August 2016, 02:33 AM
Problem solved! As it turns out, gdm needs to be installed.

I checked the file /etc/systemd/system/display-manager.service. It did not exist. I checked a working system and found that display-manager.server existed and was really a symbolic link to /usr/lib/systemd/system/gdm.service. This file also did not exist on the non-working computer.

A search of rpm showed that the working computer has gdm installed.

I installed gdm and that brought in about 30 dependencies. Rebooted, and now it goes to a graphical login screen.

Thanks - Bill Gee
There is no telling why gdm was gone.