When to use old-release.ubuntu.com and when to use archive.ubuntu.com

If you are running a old version of Ubuntu, probably you will need to amend your /etc/apt/sources.list file to have "old-release" as the URL. As those older versions of packages may have been moved over to here.

deb http://old-releases.ubuntu.com/ubuntu/ lucid main restricted universe multiverse

deb-src http://old-releases.ubuntu.com/ubuntu/ lucid main restricted universe multiverse

deb http://old-releases.ubuntu.com/ubuntu/ lucid-updates main restricted universe multiverse

deb-src http://old-releases.ubuntu.com/ubuntu/ lucid-updates main restricted universe multiverse

deb http://old-releases.ubuntu.com/ubuntu/ lucid-security main restricted universe multiverse 

deb-src http://old-releases.ubuntu.com/ubuntu/ lucid-security main restricted universe multiverse

If you are running the later version of Ubuntu, probably you will be getting as below, which is correct.

root@ubuntu:/home/anthony# egrep -v '^#|^$' /etc/apt/sources.list

deb http://us.archive.ubuntu.com/ubuntu/ xenial main restricted

deb http://us.archive.ubuntu.com/ubuntu/ xenial-updates main restricted

deb http://us.archive.ubuntu.com/ubuntu/ xenial universe

deb http://us.archive.ubuntu.com/ubuntu/ xenial-updates universe

deb http://us.archive.ubuntu.com/ubuntu/ xenial multiverse

deb http://us.archive.ubuntu.com/ubuntu/ xenial-updates multiverse

deb http://us.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu xenial-security main restricted

deb http://security.ubuntu.com/ubuntu xenial-security universe

deb http://security.ubuntu.com/ubuntu xenial-security multiverse

After you have done so, do an update on the index files.

root@ubuntu:/home/anthony# apt-get update