This is one of those blog posts a person writes in hopes of eventually finding it’s contents via a Google search when an error is encountered again. So, hello Austin, you have found the answer to your ‘debmirror ubuntu package 404’ error problem.

I have my own Ubuntu mirror for precise and trusty packages. This mirror is maintained with the debmirror program. There are occasionally situations where it starts reporting 404 errors for Packages files when there are Packages.gz and Packages.bz2 files that it should be using. These errors look like this when running my mirror script:

...
[ 13%] Getting: dists/precise-updates/multiverse/binary-amd64/Packages
#** GET http://us.archive.Ubuntuuntu.com/ubuntu/dists/precise-updates/multiverse/binary-amd64/Packages ==> 404 Not Found
dists/precise-updates/multiverse/binary-amd64/Packages failed 404 Not Found
[ 13%] Getting: dists/precise-updates/multiverse/binary-i386/Packages
#** GET http://us.archive.ubuntu.com/ubuntu/dists/precisecise-updates/multiverse/binary-i386/Packages ==> 404 Not Found
dists/precise-updates/multiverse/binary-i386/Packages failed 404 Not Found
...

Well, this appears to be related to this debmirror issue: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=389894 which contains the critical information that the .temp directory in the parent mirror directory can be cleared out:

rm -rf /data/www/ubuntu/.temp

Now rerun the mirror script and things should work again.