Ubuntu apt-get-update fails with 404
Archived
Written in June 2011. Kept as it was, so versions, links and details may be out of date.
I went to update my Nagios server running Ubuntu Server 8.04 and received a 404 error when I tried to update the repositories. Something along the lines of 404 Not Found [IP: xx.xx.xx.xx]. Obviously, 8.04 is EOL so I guess when that happens they also move the official repositories too. Fix it with the following.
Edit /etc/apt/sources.list
Replace all references of archive.ubuntu.com with old-releases.ubuntu.com