Fix GNOME GUI Login After Upgrade to Debian 10 Buster (VirtualBox VM)
Hello!
Yesterday I upgraded my old Debian VirtualBox VM from Debian 9 stretch to Debian 10 buster.
After going through all the usual upgrade steps from the official documentation and rebooting, I found myself waiting for the GNOME user selection in order to log in. Except that it was stuck with the gray background and nothing except the mouse cursor was showing up or working.
I switched to a text-only terminal (Ctrl+Alt+F5) and logged in via command line. Looking at /var/log/syslog I found the following messages repeating over and over:
gnome-shell[1281]: Failed to set CRTC mode 1448x953: Invalid argument kernel: [ 192.917346] [drm:drm_crtc_helper_set_config [drm_kms_helper]] ERROR failed to set mode on [CRTC:29:crtc-0]
1448x953 is the resolution I am using for the VM.
This current VM was created back when Debian 7 wheezy was still current, and I knew that a more recently created VM (originally with Debian 9 stretch) was working fine after upgrading to 10, so I figured that the info about the resolution from gnome-shell might have something to do with the VM's settings.
Sure enough, I found out that there were about a handful of settings that were different, most likely because over time VirtualBox defaulted to slightly different settings depending on my hardware, the template for the OS I selected (different Debian major releases) and the VirtualBox release itself. A couple of VM starts and configuration changes later I narrowed the problem down to the following VM setting:
Display => Screen => Video Memory
I raised the original 12 MB to 16 MB and thankfully the next boot showed the GNOME login mask as per usual!
Surely this is a very edge case kind of scenario, but I am hoping that this might help you in case you come across the same problem. All the other search results I found regarding roughly the same error message in the logs were about different things.
Thanks for reading!