ASP.NET FileUpload in UpdatePanel - still not working

Question

Attempting to use a FileUpload or AsyncFileUpload control in an updatepanel on a NET 4.5/C# web application.

I\'ve tried using either standard Scriptmanager or ToolK

Answer 1

Adding the button to the UpdatePanel's trigger tag, I got it working:

I did not have to do anything different server-side (like user5159158's answer).