Error: /boot/vmlinuz-4.15.0-142-generic has invalid signature

cn flag

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

System setup

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:

P5 (Ubuntu...


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.

user10489 avatar
in flag
Try booting an older kernel under advanced.
cn flag
@user10489 like I said, same problem
user10489 avatar
in flag
It should be possible to boot rescue media, possibly including the install disk (use the Try... option) and use that to reinstall a working kernel. But if this was disk corruption, I would not expect *all* kernels to be corrupted. I think something else is wrong.
cn flag

For people who may have such problem in the future:

I fixed the problem (without understanding it of course) by using the "Boot Repair Disk" from

I followed instructions and chose "recommended repair" and somehow the problem got fixed.

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