The WWW object, when running in the Unity Editor, passes a wide-open Accept header (value */*) and does not include the Accept-Encoding header.

The HTTP specification states that failing to include an Accept-Encoding header indicates that the client can accept all encodings.

As a result, the crossdomain.xml file is sent to Unity gzipped/compressed, which our WWWCurl object cannot handle. It treats the data as garbage and throws an error indicating that Unity could not retrieve the crossdomain.xml file.

This prevents _all_ WWW requests from working on web servers that serve compressed/gzipped content; this is most high-volume websites out there today.

This is a problem for all platforms that use curl (Unity editor, standalone platforms).