OK, I understand what the messages means, but I\'m really not sure what\'s causing it. I\'m using Safari and the Web Inspector on Mac OS X, by the way.
I\'v
Solved!
I have had this error for several days. It was driving me crazy because it didnt allow me to use firefox firebug's script debugger. Finally, my error was solved when I removed an empty url in a "background-image: url()" style property.
This has been so much a pain than I really hope somebody can use this advice.
This bug seem to have resurfaced (Noticed it November 2010)
I think the WebKit bug reports involved are this one and this. Essentially it boils down to incorrect cache handling when doing an If-Modified-Since
which get a 304
response.
You need to use a tool to view the HTTP headers sent with the file, something like LiveHTTPHeaders or HTTPFox are what I use. If the files are sent from the webserver without a MIME type, or with a default MIME type like text/plain, that might be what this error is about.