Install initramfs-tools-core by entering the following commands in the terminal:
sudo apt update sudo apt install initramfs-tools-core
Description:
generic modular initramfs generator (core tools)
This package contains the mkinitramfs program that can be used to create a bootable initramfs for a Linux kernel. The initramfs should be loaded along with the kernel and is then responsible for mounting the root filesystem and starting the main init system.
Version: 0.130ubuntu3
Section: utils