Package: linux-image-4.9.0-6-amd64 The update for package linux-image-4.9.0-6-amd64 from 4.9.82-1+deb9u3 to the newest 4.9.88-1 breaks the autostart of GDM. This was on a fresh install of Debian 9 (stable).
When I did the update after installing I couldn't login with GDM after reboot, the boot would freeze. And I know that the NVIDIA drivers (version 375.82-1~deb9u1) weren't loaded because the fan on my graphics card are ramped up when the NVIDIA driver is not loaded (so when the driver loads the fan will go silent). I actually reinstalled the system a couple of times and the error would occur every single time. Only installing the NVIDIA drivers after install and not updating works just fine so it's not the NVIDIA drivers that are erroneous. I found the error by installing updates one by one. And after updating the kernel the error would appear. Anyway the system refused to load GDM and the only way I could log in was by switching to another TTY and log in from the command line. However soon after logging in (usually by the time I had written a couple of commands) GDM would start and I could then log in from the GUI and from then on everything would work just fine. GDM would however not start if I didn't log in from the command line, instead the system would just hang indefinetly (I actually left it on for about 30 min while going on lunch). I ran 'systemctl status gdm3' right after logging in on TTY2 in and it stated that it was indeed running but it wouldn't show the login screen or load the NVIDIA drivers (since my graphics cards fans were going full blast). There also was no errors in any logs from what I could see. The gdm3 folder in /var/log was completely empty. Rolling back to kernel version 4.9.82-1+deb9u3 resolved the problem.