Using SWFUpload v2.2, Firefox 3, IE 8, Flash 10 In my ASP.NET application all uploads are being processed by upload.aspx (I have the correct upload_url set in the settings o
Use an HTTP trace/debugging proxy to see if anything is actually being sent to the server at all and what response is being received, if any. Charles is my favorite and works great with Flash (and everything else HTTP). WireShark and Fiddler are other options.
Charles http://www.xk72.com/charles/
WireShark http://www.wireshark.org/
Fiddler http://www.fiddler2.com/fiddler2/