I had Ubuntu Linux installed on my HD and working for several years. I usually boot the computer every day and turn in off in GUI for the night. Today, without me changing anything I suddenly see this upon powering up:
GNU GRUB version 2.04 (I normally don't see this, I get taken straight to login screen)
Advanced options for Ubuntu
and from here if I hit Enter, or any of the "advanced options", I get
Error: /boot/vmlinuz-4.15.0-142-generic has invalid signature
Error: you need to load the kernel first
I have not changed anything since last proper power-off, I am sure of that.
ASUS Mobo and Bios shows the one hard drive, and two boot options:
Originally I had them in the order above, if I change the order or disable any of them, leads to the same problem.
Does anybody have an idea, is hard-drive bad, can I fix it, or is Linux installation gone bad, can I fix it, or do I not know how to boot in this new situation that I have not encountered before?
I only have one hard-drive, and on that I only have Ubuntu. I know how to replace HD and I know how to reinstall Ubuntu from scratch, but I would rather not have to do that.