Update Panel is not working in SharePoint 2013. It is working in SP2010. In Internet Explorer, it is working fine but in Firefox, the page is refreshed.
There appears to be some sort of change in the postback mechanism that's used by SharePoint and ASP.NET in SP2013.
In Visual Studio, add a reference to Microsoft.Practices.SPG.AJAXSupport.dll. Add a SafeScriptManager control to your page and set the EnableUpdatePanelSupport flag to true. This changes the postback script that is needed for the UpdatePanel control to work in a SharePoint environment. The following code demonstrates how to add a SafeScriptManager control to a page.