Created attachment 800631 [details]
Xorg.1.log

There was reported something on the mailinglist about similar issues but I do
not think my exact issue was discussed in there.

When I updated this morning my TW machine (most likely not the 20190318
snapshot) and rebooted I could not enter X/Gnome anymore.
Bootsplash and GDM still worked correctly but starting Gnome (or any other
desktop) failed completely.

My hardware:
wolfgang@ox:~> inxi -Gxx
Graphics:  Device-1: Intel HD Graphics 620 vendor: Lenovo ThinkPad X1 Carbon
5th Gen driver: i915 v: kernel 
           bus ID: 00:02.0 chip ID: 8086:5916 
           Display: server: X.org 1.20.4 driver: i915 compositor: gnome-shell
tty: 113x43 
           Message: Advanced graphics data unavailable in console. Try -G
--display 

The Xorg.1.log file I could save before I had to roll back is attached.