Neal Becker writes:
Booted up and X dies.
Messages in /var/log/Xorg.0.log.old include
46:[ 20.239] (EE) systemd-logind: failed to get session: PID 954 does
not belong to any known session
75:[ 20.251] (EE) Failed to load module "nv" (module does not exist,
0)
That's not nouveau. That's Nvidia's binary blob.