Dear Maintainer,
During an apt installation :
apt install dmraid gpart jfsutils kpartx reiser4progs reiserfsprogs udftools
this error dropped during process :
Processing triggers for initramfs-tools (0.140) ...
update-initramfs: Generating /boot/initrd.img-5.10.0-6-amd64
/usr/sbin/mkinitramfs: 329: cd: can't cd to /etc/initramfs-tools/scripts
I created this folder : mkdir /etc/initramfs-tools/scripts
ran : update-initramfs -u
The error is gone.
Perhaps this folder needs to be checked for existence and create it somewhere in initramfs-tools related scripts ?