If you install microcode-initrd and then remove it, after the FIRST update-grub, reference to microcode.cpio. but /boot/microcode.cpio don't exists anymore, causing boot failure.
This problem only occure when using os-prober AND having SUBMENU enabled in grub.
This is due to use of /usr/lib/linux-boot-probes/mounted/40grub2, in os-prober, wich use grub.cfg, but when update-grub run, it's grub.cfg.new which is the new reference.
I propose managing grub.cfg.new in 40grub2 :
<code>
96c96,101
< if [ -e "$mpoint/boot/grub/grub.cfg" ] && \
---
> # If fresh grub.cfg.new exists, we where in update-grub/grub-mkconfig generation cycle
> GRUB_NEW=$(find ${mpoint}/boot/grub/ -maxdepth 1 -type f -name grub.cfg.new -mmin -5 || true)
> if [ -n "${GRUB_NEW}" ];then
> debug "parsing grub.cfg.new"
> parse_grub_menu "$mpoint" "$partition" "$bootpart" < "$mpoint/boot/grub/grub.cfg.new"
> elif [ -e "$mpoint/boot/grub/grub.cfg" ] && \
<code>
Status changed to 'Confirmed' because the bug affects multiple users.