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.