Ubuntu
grub2 package

Monitor unable to display grub bootloader

Asked by samuel

Whenever I boot my computer, the monitor just says, INPUT SIGNAL OUT OF RANGE change settings to 1600x900 -60Hz, instead of displaying grub bootloader, I have tried changing the line in /etc/default/grub from #GRUB_GFXMODE=640x480(this might not be the exact number, I can't quite remember what it was) to GRUB_GFXMODE=1600x900, and then running update-grub but it hasn't worked, does anyone have any ideas.

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delance
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delance (olivier-delance) said : 		#1

Edit file /etc/default/grub.
You will find a line looking like #640x480
Remove the "#" before the resolution.
Save file and run command:
   sudo update-grub
and reboot.
You can also try native resolution of monitor instead 640x480.

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samuel (samuel-h) said : 		#2

the only line I could find like that was "#GRUB_GFXMODE=640x480" and as I said, I already changed that to my native resolution, uncomented and ran sudo update-grub, but that didn't work, is there anything else that could be wrong

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Sam_ (and-sam) said : 		#3

You could try:
GRUB_GFXPAYLOAD_LINUX=keep

Basically vbeinfo of grub and framebuffer of graphic card must support the same modes.
Example, if vbe supports 640x480+16 and graphic card not may result in trouble ahead.

To generate vbeinfo of grub, press 'C' key on grub menu which will enter the specific grub-console like this:
grub >
Enter:
vbeinfo

## Note supported modes, the last line also lists the preferred mode.

To list supported modes of graphic card, open a terminal: ctrl+alt+t
Enter:
sudo hwinfo --framebuffer

## In case ignore dbus errors.

Compare the outputs, take the one which is supported from both and add it to /etc/default/grub.

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Sam_ (and-sam) said : 		#4

Correction of #3
Example mode is 640x480x16 (which is pixel size and color depth).

Forgot to mention, to leave grub-console press ESC key.

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Best delance (olivier-delance) said : 		#5

Could you try with GRUB_GFXMODE=640x480 instead of native resolution of screen.

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samuel (samuel-h) said : 		#6

Ah, one problem, I can't view the grub-console as my monitor refuses to display that as well.

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delance (olivier-delance) said : 		#7

Follow https://help.ubuntu.com/community/Grub2#Reinstalling_GRUB2 with chroot method.
Before running sudo-update grub , edit the file /etc/default/grub.

You could try also boot-repair, but I never tried it.

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samuel (samuel-h) said : 		#8

Thanks delance, that solved my question.