Bug#1120609: gdm3 fails to start after upgrade to 49.1-6

[Brent S. Elmer, Ph.D.]

On Thu, 2025-11-13 at 09:57 +0000, Simon McVittie wrote:
> Control: tags -1 + moreinfo
> 
> On Wed, 12 Nov 2025 at 21:38:29 -0600, Brent wrote:
> > gdm3 fails to start after upgrading.  I get the black screen with a
> > blinking
> > cursor in the top left corner.
> 
> We will need more information than this: the same upgrade has worked 
> successfully for others. Please check the systemd Journal for log 
> messages that occur during the failed startup.

Including the journal for the failed boot using the official debian
kernel 6.12.48+deb13-amd64. journalctl.txt


> > Kernel: Linux 6.12.48251025 (SMP w/2 CPU threads; PREEMPT)
> > Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_WARN,
> > TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
> 
> This doesn't look like an official Debian kernel, so one possible
> cause 
> is if your (presumably locally-built) kernel doesn't support a
> required 
> feature.

Tried using debian official kernel 6.12.48+deb13-amd64.  Did not make
any difference.

> 
> Is that proprietary/out-of-tree module a version of the Nvidia 
> proprietary driver?  If yes, what version?
> 

Yes it is the proprietary nvidia module version 550.163.01-3

> > /etc/gdm3/daemon.conf changed:
> > [daemon]
> > WaylandEnable=false
The journalctl.txt included is with WaylandEnable=false

journalctl_new.txt is with WaylandEnable=false commented out.
This got a little farther as gdm actually started and let me attempt to
login.  After entering userid and password I got a blank screen and the
screen came back to the login screen.  If I try to login again it said
someone was already logged in.  Gnome never starts.
> 
> GNOME 49 only supports Wayland sessions. gdm3 can still launch X11 
> sessions as the session you log in to (tested with cinnamon), but the
> gdm3 greeter (the login prompt) is now always a Wayland session, and
> so 
> is a GNOME login session.
> 
>      smcv