The Problem grub-rpi3.efi is built on RPI3 image build stage, and it is missing a crucial module for password prompt: # efibootmgr -v -v Could not read variable 'BootNext': No such file or directory error trace: vars.c:332 vars_get_variable(): open(/sys/firmware/efi/vars/BootNext-8be4df61-93ca-11d2-aa0d-00e098032b8c/raw_var, O_RDONLY) failed: No such file or directory lib.c:139 efi_get_variable(): ops->get_variable failed: No such file or directory Could not read variable … [Read more...] about Unable to set a GRUB password on a Raspberry Pi 3 system