Install linux-headers-4.15.0-20 by entering the following commands in the terminal:
sudo apt update sudo apt install linux-headers-4.15.0-20
Description:
Header files related to Linux kernel version 4.15.0
This package provides kernel header files for version 4.15.0, for sites that want the latest kernel headers. Please read /usr/share/doc/linux-headers-4.15.0-20/debian.README.gz for details
Version: 4.15.0-20.21
Section: devel