Failed to fetch http://security.ubuntu.com
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/quantal-security/main/binary-amd64/Packages 404 Not Found [IP: 91.189.91.14 80]
This is happening because you’re on an unsupported/old version of Ubuntu.
One way to fix it:
- nano /etc/apt/sources.list
- Change all entries referring to http://archive.ubuntu.com/ubuntu to http://old-releases.ubuntu.com/ubuntu