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

[Simon McVittie]

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.

>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.

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

>/etc/gdm3/daemon.conf changed:
>[daemon]
>WaylandEnable=false

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