Ubuntu 11.04 black screen fix (after install or upgrade)

I have been stumped for the last two days with my Ubuntu install.
I naively upgraded to 11.04 without checking the Ubuntu release notes… Turns out their is a known bug affecting Ubuntu ARM installs.

I upgraded and low and behold, black screen….When I rebooted I could see the Ubuntu logo then poof, darkness.
I borrowed another PC and Google’d a bit and found some forum discussions.
One that got my attention was http://ubuntuforums.org/showthread.php?t=1742352,

The fix suggested on there is to do the following:

sudo gedit /etc/default/grub

Edit the two lines (GRUB_CMDLINE_LINUX_DEFAULT and GRUB_CMDLINE_LINUX) to read as follows: 

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor vga=792"

sudo update-grub
#need to reboot
#sudo reboot

I modified the suggestion a bit when it didn’t work following https://help.ubuntu.com/community/BootText and added the last bit vga=792.
At first that didn’t work either and I was reading around on the ubuntu help pages here https://wiki.ubuntu.com/Kernel/Debugging/Backlight  and it mentioned that there may be a problem when using AC but on DC it disappears or visa versa so I unplugged my laptop’s charger and nothing happened, for a moment. I randomly tried to increase the brightness and voila… it shines!
My backlight is back and after a reboot to test it, it all works fine.
if the above fails try

echo 9>/sys/class/backlight/acpi_video0/brightness

It didn’t work for me but there was a report of it working for others on the Ubuntu forums.

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6 Responses to Ubuntu 11.04 black screen fix (after install or upgrade)

  1. solomon says:

    hi i ve the same problem . . But then am pretty new to ubuntu so could u temme where i should put those codes ? ?

    • Courtney says:

      You type the commands into the terminal. So click the Ubuntu icon/logo in the top left corner and search for “terminal”
      When its opened, copy and paste the following:

      sudo gedit /etc/default/grub

      This will ask you to type in your password because you’ve used “sudo”, enter your password and then press enter. The password won’t show up as you type.
      When the file opens in the text editor, look for the two lines mentioned in the post and edit the file as above…hope that helps

  2. Casey says:

    Hey there,

    I tried modifying the string, and at first, it worked. The light came up as it should have, but in the log-in, it continued to flicker.
    Also, beforehand, I tried the echo command and it didn’t work either. Any ideas?

    • Courtney says:

      I’d recommend using 11.10, + a new version of Ubuntu is due to be released in a month or so. Both 11.10 and the new version address some of the issues I’ve covered on my blog, including this

      • Joel Unzain says:

        I have an acer aspire 5736z and this fixed the problem. I just installed Ubuntu 12.10 and I had to go outside to see what was on my screen. Make sure after you reboot to use the option to increase the brightness. Only then, the screen will light up again!. Cheers!!!

        • zcourts says:

          Thanks for reporting back and I’m glad it helped.

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