Nvidia-driver-470 failed to boot gdm3

Here is bug-report.
I boot ubuntu 18.04,and the console says
UID121 start…
UID121 end…
UID 121 start…

UID 121 is gdm3. I think that gdm3(xorg) occurs this error.
But I don’t know how to deal with.
nvidia-bug-report.log.gz (399.2 KB)
Xorg.0.log (40.3 KB)

I tried the following things

  1. Nouveau OFF
  2. comment out WaylandEnable=false on /etc/gdm/custom.conf

Please help me

Hello @orihara.yuriko and welcome to the NVIDIA developer forums.

Are you actually working with NVIDIA MOSAIC? If not I suggest we move your topic to a more fitting category, like Drivers - Linux, Windows, MacOS - NVIDIA Developer Forums
or Graphics / Linux - NVIDIA Developer Forums

Regarding your issue at hand. From the logs you sent I can see that you have still have a version 390 driver installed, which will invariably cause problems.

I recommend you purge all NVIDIA drivers first and then install the most current one that is certified by UBUNTU, which should be 515, but 470 should be fine as well.

I hope that helps.