When I boot up with 2 monitors, or when I connect the second monitor to my laptop, I can change brightness of the laptop screen in the usual sense.

After disconnecting the second monitor, when I change the brightness, the animation at the top right corner seems to be changing, but it doesn't effect the screen brightness.

the value in /sys/class/backlight/acpi_video0/brightness does change, so writing there is not the solution either.

Any clues?

Ubuntu 14.04 LTS, 3.13.0-30-generic #55-Ubuntu SMP Fri Jul 4 21:40:53 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

Thanks in advance.

  • 2
    I'm having the same problem. Let me know, if you find a solution.
    – pmichna
    Jul 22, 2014 at 15:48
  • strange thing happened, after a couple of updates (standard upates) it got fixed. I'm not sure what package/library fixed it. My latest kernel is as Ubuntu 14.04 LTS, 3.13.0-33-generic #58-Ubuntu SMP Tue Jul 29 16:45:05 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
    – eaydin
    Aug 14, 2014 at 16:14

1 Answer 1


Intel graphics? Thent this is probably a known bug: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1308674

I found that updating the kernel helped to resolve that particular issue, but it comes at the expense of the screen not being able to be fully black, anymore.

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