Display brightness cannot be adjusted 18.04

An alternative method is to install a PPA and brightness APP which also adjusts gamma - AWESOME!, and ... for any individual screen TOO!

Here are the 3 simple steps:

$ sudo add-apt-repository ppa:apandada1/brightness-controller
$ sudo apt update
$ sudo apt install brightness-controller

Then find it ...

Brightness Controller

in your App's/Accessories

Always Trying to help, Mark

I had the same issue on a Dell XPS 13. Found this link that solved the problem for me : https://bugs.archlinux.org/task/58296#comment168869

What I did:

• changed the content of /etc/default/grub by adding video.only_lcd=0 to GRUB_CMDLINE_LINUX_DEFAULT
• updated grub with sudo update-grub

After restarting the laptop, I was able to control the brightness.

I had the same problem some years ago and was having the same problem again after installing ubuntu 18.04. it was a kernel problem then, and i think it may be a kernel problem now.

After updating the kernel the problem was fixed for me.

To update kernel see: Updating kernel question

To download last stable kernel (which worked for me): http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.16.6/

In my case i downloaded:

  linux-headers-4.16.6-041606_4.16.6-041606.201804300418_all.deb

  linux-headers-4.16.6-041606-generic_4.16.6-041606.201804300418_amd64.deb

  linux-image-unsigned-4.16.6-041606-generic_4.16.6-041606.201804300418_amd64.deb

  linux-modules-4.16.6-041606-generic_4.16.6-041606.201804300418_amd64.deb