This was a problem for me with kubuntu 21.04 as well on a MacBookPro 11,2. The workaround did the trick. Exact workaround command follows:
/boot/efi/EFI# cp -b ubuntu/grubx64.efi ubuntu/shimx64.efi /boot/efi/EFI# cp -b ubunt/grubx64.efi BOOT/BOOTX64.EFI
This works immediately.
This was a problem for me with kubuntu 21.04 as well on a MacBookPro 11,2. The workaround did the trick. Exact workaround command follows:
/boot/efi/EFI# cp -b ubuntu/grubx64.efi ubuntu/shimx64.efi
/boot/efi/EFI# cp -b ubunt/grubx64.efi BOOT/BOOTX64.EFI
This works immediately.