I've been working with Appcache for quite some time, but I recently took a couple of weeks to develop a different project. When I returned to my offline project, I started getting this error every time I try to download the contents of my manifest:
Application Cache Error event: Manifest fetch failed (9)
This is followed by 2 addresses; the file and line number of the page that calls the manifest (on right of same line), and the relative url of the manifest itself (on a second line). The download of the individual resources does not begin.

Now, other folks work on this project, but I'm the only guy who touches anything that as much as smells of offline. The issue doesn't appear to be related to any of my usual suspects, like a syntax error in the manifest (tried clearing all the files, just to be sure), the manifest being served incorrectly, or something wrong with one of the files being cached. I don't think it's a memory problem, as I have over 30 gigs of space outside of the size of the files I'm caching. Furthermore, this worked 2 weeks ago, so I'm assuming that there isn't something wrong with my setup. However, nobody seems to know what the hell this error is; nobody even seems to be getting this error. I can't find anything online to describe what this issue is. Hence, my question is:

What does Manifest fetch Failed (9) mean?

My browser is Chrome on Windows 7, and is up to date.