I installed the
nvidia-driver-410 package from the
graphics-drivers ppa. I could not boot, with the following message repeated a few times:
PKCS#7 signature not signed with a trusted key
It looked like the easiest solution was to disable SecureBoot (which I've done both in UEFI and by using
mokutil --disable-verification), but the problem persisted. I then reenabled SecureBoot, made a new key, signed all the nvidia modules I could find (nvidia.ko, nvidia-uvm.ko, nvidia-drm.ko, nvidia-modeset.ko, nvidiafb.ko, forcedepth.ko) and enrolled the key according to this previous question. I still could not boot.
Now if I look in
journalctl to inspect my last boot log, I see there are actually way more signature failures than I was being shown. They still exist for the nvidia modules plus a ton of other random modules like USB drivers. I would upload the journalctl log but I can't seem to enable networking in the recovery root prompt without causing the system to hang.
I am hitting this problem both with kernel 184.108.40.206 and 4.18.15.