Signal out of range message at boot time

I have gone through all the posts and I am pretty sure I know how to fix it, but I can't seem to be able to get to a prompt.

I see GRUB loading and then nothing from that point forward. Immediately after post I see a flashing cursor in the upper left corner. A few seconds later the monitor displays a message saying signal out of range. No keystrokes at any point give me access to a login prompt. I'm not sure what to do at this point.

I installed 16.04 and 17.10 with the same result.

Solution 1:

At first you should determine specification of your monitor - especially its native resolution.
Then you can adjust it manually in configuration file.

Try the following:

1. press Shift during boot to access GRUB menu

2. in GRUB press e, then

   • add nomodeset to the end of linux line OR
   • add vga=795 (1280x1024, see other options here) to the end of linux line

3. then hit Ctrl+x or F10 to boot.

Remember good value of vga= and then place it in /etc/default/grub:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash vga=795"

Then execute sudo update-grub and reboot.

Solution 2:

On live media (eg. Ubuntu install media), I've had this issue occur because of a bad write to media.

If you're using live media, did you

(a) Validate your ISO ?

https://tutorials.ubuntu.com/tutorial/tutorial-how-to-verify-ubuntu#0

(b) Validate your write to install media

https://help.ubuntu.com/community/Installation/CDIntegrityCheck

Ubuntu 20.04 & later media self-verify, but if this issue occurs on the first boot, you won't be able complete the validation (or at least see results), so I usually shutdown using SysRq keystrokes, then attempt to boot the thumb-drive on another box. Not all boxes will experience this issue, but if I have problems on the second box, I assume it was a bad-write and usually return to check the ISO & re-write the ISO to my media (usually thumb-drive). I have booted before on a third box for confirmation of failed boot, but usually don't consider this necessary.