Anything I have tried didn't work. Currenly I have following code to change asp.net session cookie expiration date and path, but asp doesn't want to listen to me. I sends same cookie in Set-Cookie header two times sometimes, sometimes it sends it's default cookie ignoring path and expiration date, sometimes it sends everything as expected, and sometimes it doesn't send Set-Cookie at all. What should I do. This drives me nuts :(

My code in Global.asax

protected void Application_PreRequestHandlerExecute(Object sender, EventArgs e)
{
  /// only apply session cookie persistence to requests requiring session information
  if (Context.Handler is IRequiresSessionState || Context.Handler is IReadOnlySessionState)
  {
    var sessionState = ConfigurationManager.GetSection("system.web/sessionState") as SessionStateSection;
    var cookieName = sessionState != null && !string.IsNullOrEmpty(sessionState.CookieName)
      ? sessionState.CookieName
      : "ASP.NET_SessionId";

    var timeout = sessionState != null
      ? sessionState.Timeout
      : TimeSpan.FromMinutes(20);

    /// Ensure ASP.NET Session Cookies are accessible throughout the subdomains.
    if (Request.Cookies[cookieName] != null && Session != null && Session.SessionID != null)
    {
      Response.Cookies[cookieName].Value = Session.SessionID;
      Response.Cookies[cookieName].Path = Request.ApplicationPath;
      Response.Cookies[cookieName].Expires = DateTime.Now.Add(timeout);
    }
  }
}