(I've asked this question on AskUbuntu with no response after 4 days.)

Before showing GRUB, it shows

Unable to trigger tcg2 final events table: Invalid Parameter
Something has gone seriously wrong: import_mok_state() failed
: Invalid Parameter

and machine power off.

It's my first time to install Ubuntu 19.04 on this machine, DELL T5810 with UEFI. The Ubuntu installation was fine, enrolling the Machine Owner Key MOK caused the boot error. When I ran sudo apt install virtualbox. virtualbox installation prompted me to enroll MOK; I rebooted the machine, and enrolled MOK. Then it entered the above dead state.

Booting from Ubuntu's LiveUSB installer shows the same error message. Luckily, I can still boot into Windows 10 on the same machine. I just want to revert enrolling MOK. Not installing Virtualbox in future is acceptable.

What I've tried:

  1. Searching the error message leads to mokutil, but I can't boot into a linux now.
  2. I also tried reset BIOS, but it doesn't work at all (I have to repair windows boot).
  3. Open EFI partition in Windows, deleted EFI/ubuntu, EFI/BOOT/fbx64.efi, EFI/BOOT/mmx64.efi.