Show Progress Bar when uploading files using AJAX UpdateProgress in ASP.Net

Here Mudassar Ahmed Khan has explained how to show (display) loading Progress Bar when uploading files using AJAX UpdatePanel and UpdateProgress in ASP.Net in C# and VB.Net. ASP.Net FileUpload control requires PostBackTrigger while ASP.Net AJAX UpdateProgress works with AsyncPostBackTrigger of AJAX UpdatePanel. This article explains how to use ASP.Net AJAX UpdateProgress with PostBackTrigger so that when file is uploading a loading Progress Bar can be shown.