: Why am I seeing 404 requests for crossdomain.xml in my server logs? My website is recording a lot of 404 errors, from numerous sources, for a file crossdomain.xml. Does anyone know what this

@Voss4911412

Correct, the crossdomain.xml file is requested to determine if Flash and Silverlight apps are "allowed" to access your website. Personally, I think it's a really dumb convention, but.. it's out there.

For Microsoft Silverlight


When calling a cross-domain service, Silverlight will check for the existence of clientaccesspolicy.xml first. This is the format defined by Silverlight and provides a pretty flexible way to define who can access what services. If not found, it will then default to look for crossdomain.xml, which is the file format implemented for Adobe Flash. It is important to note that this file will also still work for most public web services.


For Adobe Flash


Another change to the Flash Player 7 framework is the use of cross-domain policy files. A policy file is a simple XML file that gives the Flash Player permission to access data from a given domain without displaying a security dialog. When placed on a server, it tells the Flash Player to allow direct access to data on that server, without prompting the user to grant access.


Probably easiest to add this file if you don't want the 404s, and decide whether or not you want to allow Flash and Silverlight access to your website without a security prompt.

Vote Up Vote Down

@Kaufman445

This file contains permissions for flash applications. It is requested by any flash app embedded on your site. (Just like favicon or robots.txt)

Vote Up Vote Down