Update Progress Bar Dynamic Change Label

Use UpdateProgress control, set the label text is Please wait while processing...

put the below code at script tag

var prm = Sys.WebForms.PageRequestManager.getInstance();

prm.add_initializeRequest(InitializeRequest);

function InitializeRequest(sender, args)
{

// Get a reference to the element that raised the postback,

// and disables it.

$get(args._postBackElement.id).disabled = true;$get('LblHolder).innerHTML= = "This is a test";


}