Hi, Bug cannot be fixed see: https://wiki.debian.org/Teams/Dpkg/FAQ#Q:_What_are_the_filesystem_requirements_by_dpkg.3F
In short: Although /boot/efi must be on a vfat partition, /boot cannot be on a vfat partition. It must be on some regular linux partition where it is possible to set symlinks. Good luck to all who will struggle with this! j.