Fix "Failed to set MokListRT: Invalid Parameter" on a Mac Book Pro 2015
In Ubuntu 20.04 on some macs (mine is a 2015 MBP), at boot there is the message "Failed to set MokListRT: Invalid Parameter"
To solve it run
apt-get purge shim
mv /boot/efi/EFI/ubuntu /root/ubuntu-efi.bak #backing up just in case
grub-install /dev/sda1
References: