I was able to solve this with the information from comment #25. I booted my system with a separate system rescue CD stick (see http://www.system-rescue-cd.org/). Then, in rootshell, I did:
# chattr -i /sys/firmware/efi/efivars/Mok* # rm /sys/firmware/efi/efivars/Mok* After this, the Ubuntu installer is able to boot from stick. Note that the actual error is *not* this: Failed to open \EFI\BOOT\mmx64.efi - Not Found Failed to load image \EFI\BOOT\mmx64.efi - Not Found But this: Failed to start MokManager: Not Found Something has gone seriously wrong: import_mok_state() failed : Not Found -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1798171 Title: System fails to boot with \EFI\BOOT\mmx64.efi - Not Found To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1798171/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
