Recently the OS disk of one of my servers failed. Since the OS disk is a USB stick and I have had good experiences with Diet Pi for my raspberry pi's, I thought I'd take a look if it is also available for AMD64. Guess what, it is!
So I fired up
dd to push the downloaded image to the USB stick, popped the USB stick into the server and ran the OS for the first time. So far, so good. But then I rebooted...
After the first reboot (so the 2nd boot), I was confronted with the following error message, displayed right after trying to load the kernel and initramfs:
error: symbol 'grub_register_command_lockdown' not found.
Looking around online, I was luckily not the first or only one to have encountered this. Someone at the openmediavault forum had the same issue. In that thread another openmediaforum thread was referenced but also a bug at debian. In the bug report comment 50 from Dr. Bernd Zimmermann provides the solution (for now).
Just run grub-install manually to the correct disk (after running the dietpi installation for the first time and before rebooting for the first time):