I have upgraded to ubuntu 18.04 LTS the display brightness controls are not working. It appears that the brightness is in its lowest level and I am not able to change display brightness at all. It was working on 16.04 LTS. My laptop uses Intel Graphics card.

I have tried to solve that by creating the file /usr/share/X11/xorg.conf.d/20-intel.conf with the following content. It worked the first time, but after one reboot it remains back to the previous problem.

Section "Device"
        Identifier  "card0"
        Driver      "intel"
        Option      "Backlight"  "intel_backlight"
        BusID       "PCI:0:2:0"

What can I do?

  • Does the Screen Brightness slider in Settings > Power show at all, or is it greyed out? – Broadsworde May 10 '18 at 4:14
  • The screen brightness slider in Settings->Power does not work, the screen brightness does not change. – Claudio Diniz May 10 '18 at 12:52
  • Ok, I solved the problem by installing xbacklight and adding it to startup applications. – Claudio Diniz May 10 '18 at 14:28
  • I rebooted the computer again and the problem came back. – Claudio Diniz May 10 '18 at 18:11
  • Lenovo Z570. Intel Graphics i915. If you have two folders acpi_video0 and intel_backlight under /sys/class/backlight/ then you need to remove acpi_video0 by adding acpi_backlight=none parameter to /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT. Do not forget to run sudo update-grub and reboot – x4444 Apr 23 '20 at 3:40

I also had this problem, but on different distributions the solution was different.

Solution provided by Anas Elazhar worked well until I switched to Xubuntu:

Open the file /etc/default/grub using gedit or any other text editor. Find below line.


Change above line to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

If it doesn't work for you either try to change acpi_backlight value to video:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=video"

Also create the file /usr/share/X11/xorg.conf.d/80-backlight.conf but content is slightly different from the file that you created:

Section "Device"
    Identifier  "Intel Graphics"
    Driver      "intel"
    Option      "AccelMethod"     "sna"
    Option      "Backlight"       "acpi_video0"
    BusID       "PCI:0:2:0"

If combination acpi_backlight=video with this file doesn't work change acpi_backlight back to vendor.

And do not forget to run sudo update-grub command in terminal every time you change /etc/default/grub!

  • 1
    adding of ` acpi_backlight=vendor` was enough (+restart). Ubuntu 18.04. Samsung R510 – it3xl Apr 13 '19 at 21:08
  • 2
    XUbuntu 18.04 on Lenovo Thinkpad T480s: acpi_backlight=video and file 80-backlight.conf did the trick. – kiltek Jul 6 '19 at 18:52
  • 2
    No Joy with this answer SADLY Thanks anyway – markackerman8-gmail.com Nov 12 '19 at 22:20
  • XUbuntu 18.04 on Lenovo Thinkpad T420: acpi_backlight=video worked. – Darren Smith Mar 1 '20 at 5:55
  • I am using Ubuntu 20.04 on HP Laptop. I was getting Unknown Display in display manager because of which I was not able to add secondary monitor or adjust screen brightness. After a lot of searching I landed on this answer and it worked perfectly. acpi_backlight=vendor + sudo update-grub + restart did the trick. Thank you ! – Harshil Aug 1 '20 at 11:25

Open the file /etc/default/grub using gedit or any other text editor. Find below line.


Change above line to

  GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

This would ensure to load device specific drivers before default drivers in Linux.

Save the file and close text editor.

Open terminal and run below command to update grub.

  sudo update-grub


After reboot, try adjusting brightness using Laptop dedicated control keys. Good Luck.

  • 4
    I did that, but it does not work in my laptop. – Claudio Diniz May 18 '18 at 12:29
  • Try ducky's answer – Anas Elazhar May 23 '18 at 13:53
  • This answer successsfully made my laptop react to screen brightness keys... but it now has only one possible setting of brightness. (Haven't tried ducky's answer yet) – lucidbrot May 9 '20 at 10:22
  • Setting acpi_backlight=video instead (and running sudo update-grub && reboot ) instead of vendor worked for me – lucidbrot May 9 '20 at 10:28

Installing Brightness Controller helped me in fixing up the issue

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

You can access the Brightness Controller after download by searching for it.

  • Just added an unworkable small brightness controller window ... Useless for my rig sadly – markackerman8-gmail.com Nov 12 '19 at 22:39
  • It fails on line three because of some unsatisfiable dependency: sni-qt. – Christian Schlichtherle Nov 15 '19 at 9:41
  • Now it's been fixed – Archisman Panigrahi Jan 16 '20 at 19:37

Based on my current Ubuntu 18.04 installation (from today), I can adjust brightness at the login screen with the function keys (out of the box!). However, I am using i3 with Gnome, and after login, I am no more shown brightness controls in Gnome control centre.

Above answers didn't unfortunately work for me: Instead, using Ducky's xorg script together with Grub option made my i3 + Gnome session having undesired display behaviour and getting slower.

Anyway, at least for the case you go for a non-Gnome session (e.g. i3), I can point you to https://github.com/szekelyszilv/ybacklight which (given you have meson and ninja installed) can be built by:

  • downloading, unpacking and changing into ybacklight main directory
  • mkdir build; meson build; cd build; ninja install

or, (without those tools and if you don't want to install it in the system), by:

  • cd src; gcc ybacklight.c -o ybacklight; cp ybacklight to-your-pref-dir

and then be attached to function keys via WMs config. E.g. in i3wm, I added:

bindsym XF86MonBrightnessUp exec ybacklight -inc 10 
bindsym XF86MonBrightnessDown exec ybacklight -dec 10 

to my .config/i3/config.

Furthermore, setting brightness requires root privileges, e.g., achievable with "sudo ybacklight ..." as well as an entry to /etc/sudoers: see How can I add a new user as sudoer using the command line?

  • 1
    You can also just build it with cd src; gcc ybacklight.c -o ybacklight. To set the brightness, it needs root privileges, so I used sudo (and added an appropriate entry to /etc/sudoers). – Mark May 30 '18 at 1:04
  • Thx, absolutely right. Far better than my solution with chmod. – Mario May 30 '18 at 7:45

I've recently updated to 18.04 and I have found that changing GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub to the following

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=video"

and adding,

Option         "RegistryDwords" "EnableBrightnessControl=1"

to /etc/X11/xorg.conf under

Section "Device"

fixed the control and brightness keys issues running Nvidia 390 driver.

  • 1
    GuyFork's answer WILL brick your GTK. DO NOT USE HIS INSTRUCTIONS. – mortal Jun 27 '18 at 23:11
  • 1
    @tak I really don't see how this could affect your hardware. If you are sure, please post an answer explaining exactly what you did and what happened. – terdon Jun 28 '18 at 8:46
  • @tak maybe this will not work for everyone just like a lot of other post/instructions from various groups did not work for me. if it doesn't work for you, you can always purge remove nvidia* and try another way as i have done many times with many laptops and various releases. – GuyFork Jul 13 '18 at 18:37
  • 1
    It also broke my system. It was not loading until I remove /etc/X11/xorg.conf file in recovery mode. Do not recommend to use it. – Experimenter Jan 22 '19 at 13:37

I started the nvidia X server settings and in the x server display configuration changed the selection to X Screen0 and it worked.

The brightness control works now. Also before doing that I've changed the grub to acpibacklight=video0.

  • Welcome to Ask Ubuntu! I recommend to edit this answer to expand it with specific details about how to do this. (See also How do I write a good answer? for general advice about what sorts of answers are considered most valuable on Ask Ubuntu.) – David Foerster Aug 24 '18 at 8:44

On Ubuntu 18.04 (with xfce desktop) my brightness problem finally solved.

I opened 'Onboard Settings' under the 'Settings' menu. If your desktop doesn't have one, you can download it from Software Center.

On the 'Onboard Preferences' window, click the Layout menu, then choose the 'Full Keyboard' (Desktop keyboard with edit and function keys). Click here to view the Onboard Settings window


I managed to get Brightness control working with nvidia drivers on Debian 10.

Here is my hardware : - ThinkPad P51 - Nvidia Quadro M2200 GPU + Intel GPU

Here is how I did :

  • Go to Bios and configure display to Discrete graphics (only Nvidia GPU will be used)

  • Remove Nouveau driver if it is setup

    Add nouveau blacklist to /etc/modprobe.d/nvidia-installer-disable-nouveau.conf

    blacklist nouveau options nouveau modeset=0

    then run

    update-initramfs -u

    then reboot

  • Download and install latest Nvidia driver from Nvidia website (https://www.nvidia.com/Download/index.aspx?lang=en) Mine was version 430.50

    Open a tty console without any X Server launched (Ctrl+Alt+F3 at login page)

    Install linux headers if you don't have ( apt-get install linux-headers-`uname -r` )

    Install driver as root ./NVIDIA-Linux-x86_64-430.50.run (erase libs if requested)

That's it everyting working perfectly finally !!


After creating the file /usr/share/X11/xorg.conf.d/80-backlight.conf and rebooting, I experienced blank screen and I couldn't do anything about it. I have a dual boot machine, so I solved my problem by booting into windows, downloading software to access Linux files and then I deleted the /usr/share/X11/xorg.conf.d/80-backlight.conf that was causing the problem.

The way I solved my problem:

  1. sudo nano /etc/default/grub
  2. search and change this line GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi="
  3. sudo update-grub
  4. Reboot
  • After a few days, I faced a problem with my functions keys that turn on and off my led keyboard and also the display mode utility. So I removed the splash acpi_osi= from grub file and after the reboot, I was able to control my lost function keys. Though I lost the screen brightness control and because I didn't want to lose more time in searching I just installed the brightness controller as described by @SivagamiNambi above. – Evdokimos Theodoridis Dec 22 '20 at 12:04

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