Double PostBack inside UpdatePanel

I have a problem with ASP.NET firing a button click twice. The button is inside an UpdatePanel, but when I click it I get two postbacks, then two button clicks, 开发者_C百科then two calls to my DAL (in that order). I've never encountered this before, and changing AutoEventWireup to false had no effect. The only workaround I can think of would be to hide the functionality in a web service and handle the complications with jQuery, which I'd rather not do for a small project.

The firebug dumps are below (these both happen from one click).

Put the following script on the page after the ScriptManager.

<script type="text/javascript"> 
var postbackControl = null; 
var parm = Sys.WebForms.PageRequestManager.getInstance(); 
parm.add_beginRequest(BeginRequestHandler); 
parm.add_endRequest(EndRequestHandler); 

function BeginRequestHandler(sender, args) 
{ 
 postbackControl = args.get_postBackElement(); 
 postbackControl.disabled = true; 
} 
function EndRequestHandler(sender, args) 
{ 
postbackControl.disabled = false; 
postbackControl = null; 
} 
</script>

Could it be that you've hooked jQuery click() to the button, which is also implicitly inline hooked to onchange by ASP.NET?

jQuery.change + inline onchange fn() causes fn to execute twice

Or did you check whether you might have hooked the server-side handler twice, both declaratively in markup and imperatively in the code-behind?

Bizarrely, this seems to be caused by a dodgy ControlAdapter for buttons which adds a span inside the button tag to make sliding doors work.

writer.AddAttribute(HtmlTextWriterAttribute.Type, "button");

make no sense but works