Good evening
I just installed deb10 buster on an existing partition sda4 (replacement of another linux) in csm mode (no uefi partition)
I had no problems during the instal,I understand GRUB was not installed by debian.
I have 3 linux in multiboot,and after debian install I launch boot repair with my main linux ,and debian is now in the grub menu.
But infortunately during the boot such error occurs:
Mounting /dev/sda4 on root failed:no such device......
Busybox v1.30.1(debian 1 1 30 1 4) built in shell