If you are trying to stop the session from timeing out all the time you can do this rather than increasing the session timeout.

KeepAlive.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="KeepAlive.aspx.cs" Inherits="Pages.KeepAlive" %>  <%@ OutputCache Location="None" VaryByParam="None" %>      
    
 
     
       KEEP ALIVE 
     
 
    
  

Keep Alive.aspx.cs

using System;using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; namespace Pages { /// 
 /// Page to keep the session alive /// 
 public partial class KeepAlive : System.Web.UI.Page { //- EVENTS ------------------------------------------------------------------------------------------------------------------ #region Events /// 
 /// Page Load /// 
 /// object /// args protected void Page_Load(object sender, EventArgs e) { try { //Add refresh header to refresh the page 60 seconds before session timeout Response.AddHeader("Refresh", Convert.ToString((Session.Timeout * 60) - 60)); } catch (Exception) { throw; } } #endregion Events //--------------------------------------------------------------------------------------------------------------------------- } }

Then in your master page create an iFrame that refreshes to keep the session alive