Tecmint: If you install Debian 9 system using a netinstall CD image, your system probably will not have all the necessary repositories (from which you can install common packages), included in the apt sources list file. This can result into error like ???E: unable to locate package package-name???.
In this article, I will explain how to fix the ???E: unable to locate package package-name??? error in Debian 9 distribution.