H
Regarding this URL
http://www.codeproject.com/KB/aspnet/FlashUpload.aspx
User.Identity as System.Web.Security.FormsIdentity is always null, because the Identity is GenericIdentity, I assumed it will be as in the tutorial FormsIdentity, what is chances.
Thanks
Rather than Casting to FormsAuthentication, Simply get the cookie .ASPXAUTH (or the name specified in the web.config) and send it to flash and then let flash put it as a POST variable while uploading, then Read Request.Forms[POSTVariable] and create the FormsAuthenticationTickt as illustrated by the tutorial in the question.