Comment 171 for bug 1752053

I think I have the same issue.
Difference is that everything worked as charm until I've updated some non-nvidia packages. Since then I'm stuck to uning nouveau as none of the workarounds worked.

HW:
ROG STRIX GL503VM-FY022
nVIDIA GeForce GTX 1060 6GB

What worked fine before update:
kernel 4.15.x-x with nvidia 390 (ubuntu repository)
kernel 4.17.x with nvidia 396 (ppa)

After the update it worked one more time with 4.15.x with
options nvidia_390_drm modeset=1
in /etc/modprobe.d/xxxx.conf

Since after next reboot nothing has worked except purge-ing nvidia and switching to nouveau...

Attaching apt log for that update. mono was updated as well adding a lot of noise, but the relevant part seems to be grub:

Kibontás előkészítése: .../14-grub-efi-amd64_2.02-2ubuntu8.2_amd64.deb ...
Kibontás: grub-efi-amd64 (2.02-2ubuntu8.2) e helyett: 2.02-2ubuntu8.1 ...
Kibontás előkészítése: .../15-grub2-common_2.02-2ubuntu8.2_amd64.deb ...
Kibontás: grub2-common (2.02-2ubuntu8.2) e helyett: 2.02-2ubuntu8.1 ...
Kibontás előkészítése: .../16-grub-efi-amd64-signed_1.93.3+2.02-2ubuntu8.2_amd64.deb ...
Kibontás: grub-efi-amd64-signed (1.93.3+2.02-2ubuntu8.2) e helyett: 1.93.2+2.02-2ubuntu8.1 ...
Kibontás előkészítése: .../17-grub-efi-amd64-bin_2.02-2ubuntu8.2_amd64.deb ...
Kibontás: grub-efi-amd64-bin (2.02-2ubuntu8.2) e helyett: 2.02-2ubuntu8.1 ...
Kibontás előkészítése: .../18-grub-common_2.02-2ubuntu8.2_amd64.deb ...
Kibontás: grub-common (2.02-2ubuntu8.2) e helyett: 2.02-2ubuntu8.1 ...

i.e. grub was updated from 2.02-2ubuntu8.1 to 2.02-2ubuntu8.2.

Not sure if any of these can help, but for me nvidia has been completely broken since this update. Since then I'm constantly getting the following lines in kern.log (egrep -i '(nvidia|nvrm)'):

kernel: [ 1.675561] NVRM: loading NVIDIA UNIX x86_64 Kernel Module 396.24.10 Tue Jul 10 10:00:18 PDT 2018 (using threaded interrupts)
kernel: [ 1.682807] nvidia-modeset: Loading NVIDIA Kernel Mode Setting Driver for UNIX platforms 396.24.10 Tue Jul 10 08:53:56 PDT 2018
kernel: [ 1.685191] [drm] [nvidia-drm] [GPU ID 0x00000100] Loading driver
kernel: [ 2.543799] nvidia-modeset: Allocated GPU:0 (GPU-ca4d2121-189c-752b-9cba-302ed81038d4) @ PCI:0000:01:00.0
kernel: [ 2.595623] [drm] Initialized nvidia-drm 0.0.0 20160202 for 0000:01:00.0 on minor 0
kernel: [ 3.244611] nvidia-uvm: Loaded the UVM driver in 8 mode, major device number 236
kernel: [ 5.310256] NVRM: GPU at PCI:0000:01:00: GPU-ca4d2121-189c-752b-9cba-302ed81038d4
kernel: [ 5.310259] NVRM: Xid (PCI:0000:01:00): 61, 0ac0(2f10) 00000000 00000000
kernel: [ 12.366052] nvidia-modeset: WARNING: GPU:0: Lost display notification (0:0x00000000); continuing.
kernel: [ 15.124364] nvidia-modeset: ERROR: GPU:0: Idling display engine timed out: 0x0000987d:0:0