While updating a new installation of Kali Linux, I received the error message
Err http://http.kali.org/kali/ kali/non-free metasploit amd64 4.8.2-2014012201-1kali0 404 Not Found.
Apparently, the hostname http.kali.org points to a CDN and not all of its mirrors contain updated packages. In order to solve this I went to the Kali mirror list and chose another mirror from my continent. I then updated the file /etc/apt/sources.list accordingly (replace with your chosen mirror):
Make sure to choose a mirror from your continent, if possible.
Finally, update the package database, then try to upgrade Kali Linux again:
If the update succeeds but the upgrade still fails, try with another mirror.
If the update fails, make sure you have entered the mirror address correctly into /etc/apt/sources.list. Don’t include the trailing /README.