The download of the specified resource has failed.

Recently, "The download of the specified resource has failed." error boring me a lot.

The SSL Cert on the web server had a hostname mismatch error. This caused the problem with using xmlhttp.send() resulting in "The download of the specified resource has failed.".


The solution is:
Change
XMLHTTPClass sender = new XMLHTTPClass();
To
ServerXMLHTTP sender = new ServerXMLHTTP();

then when executing sender.send(Request);, everything is back to normal.