Problem using the ASP.NET FileUpload control in an UpdatePanel?

Answer 1

To upload a file you need to perform a full ASP.NET page postback, it does not operate over the partial postback method.

You'll need to register the button which "uploads" your file as a PostBackTrigger of the UpdatePanel's triggers.

There are lots of free (and non-free) AJAX file upload solutions, or you can easily create one, it's just a matter of putting your file upload control within an iframe and submitting the iframe page back to the server. It isn't really ajax, but it gives a visual impression of AJAX.