Since we are now using Ubuntu Server 14.04, we no longer need the Source List Subsection:
Source List
Since Ubuntu 11.04 is not supported, create a backup of the /etc/apt/sources.list file:
cp /etc/apt/sources.list /etc/apt/sources.list.backup
Then, change the contents of the original file to the following:
## EOL upgrade sources.list
# Required
deb http://old-releases.ubuntu.com/ubuntu/ natty main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ natty-updates main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ natty-security main restricted universe multiverse
# Optional
deb http://old-releases.ubuntu.com/ubuntu/ natty-backports main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ natty-proposed main restricted universe multiverse
Since we are now using Ubuntu Server 14.04, we no longer need the Source List Subsection: