It looks like your kernel command line has a custom backlight change,
which is unusual:
[ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-36-generic
root=UUID=fd7306d2-c2eb-414c-bf34-7e6c72a1fe79 ro quiet splash
acpi_backlight=vendor vt.handoff=1
Maybe try:
1. Removing the "acpi_backlight=vendor" from /etc/default/grub
2. sudo update-grub
3. Reboot
** Summary changed:
- brightness controller missing
+ brightness controller missing after installing nvidia-390
** Package changed: xorg (Ubuntu) => nvidia-graphics-drivers-390
(Ubuntu)
** Changed in: nvidia-graphics-drivers-390 (Ubuntu)
Status: New => Incomplete
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You received this bug notification because you are a member of Ubuntu-X,
which is subscribed to xorg in Ubuntu.
https://bugs.launchpad.net/bugs/1799218
Title:
brightness controller missing after installing nvidia-390
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-390/+bug/1799218/+subscriptions
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