I have a website running under IIS on Windows 7.
Everytime the webpage requests an XML file I receive a 400 Bad Request (diagnosed through firebug). If I request the XML file directly by typing it into my browser it works.
This not only happens for .xml file extensions but .xsl too; both of which contain XML data.
I found the issue.
When requesting the XML files I was adding the
If-Modified-Sinceheader which is in the HTTP spec but IIS on Windows 7 seems to return400 Bad Requestwhen this is added. Simply removing this header from the request fixes the issue.