I can't boot from USB: Error setting up gfxboot
Solution 1:
Just type help
and press Enter. It will continue to boot normally.
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/659253
Solution 2:
Try typing 'live' and hitting Enter. It worked for me just now!
Last week I was trying MX Linux 18.2 on my Samsung Chromebook 3. That distro presents a boot menu. "live" is the option that you have to choose to boot the USB image. However, I love Ubuntu and my Samsung Chromebook 3. So, I've so I've been trying to run Ubuntu on my chromebook for several years and always been presented with the dreaded message in this discussion. And, typing 'help' didn't help me in the past. So I hope this can help someone else.
I'm now running Xubuntu on my Samsung Chromebook 3. Good times!