This failure is on an external hard drive connected by USB. However, it worked flawlessly for several days.
Then, one day when I tried to start Ubuntu there appeared a Debian splash screen with grub menu. When I selected the appropriated boot item from menu screen goes black and the above mention error appeared and never finished the boot process. Process hung there.
I have read and reread all the forum topics on this subject. All I really find is discussion about it may be this and may be that, but no fixes. Found one "work around" that did not work.
Someone must know what to do about this. The suggestions about what it might be doesn't help. System won't boot and even if the suggestions were accurate, still no mention of how to correct the problem. Can anyone help?