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
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* efi/efivars/ Mok*
# rm /sys/firmware/
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