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.

Stack Underflow avatar
es flag
This worked after I disabled secure boot from the UEFI boot options.
cn flag
@StackUnderflow yea I tried that too, did not work for me. This has to be the best SO name ever, that and "Cadaver".

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.