# grub2-mkconfig -o /etc/grub2-efi.cfg
Generating grub configuration file ...
/usr/share/os-prober/common.sh: line 328: which: command not found
Adding boot menu entry for UEFI Firmware Settings ...
done

Minimal Fedora Server install. The offending part from /usr/share/os-prober/common.sh is:

umount_exec=$(which umount)
umount() {
        if ! $umount_exec $@ 2> /dev/null; then
                error "umount error, retrying after 1 sec"
                sleep 1
                $umount_exec $@
        fi
}


I do not know how this code works. We can replace "which" with "command -v", or make os-prober RPM depend on "which", or simply call "umount" or "/bin/umount" directly perhaps?