How to Check whether Session is Expired or not in asp.net

Question

I\'ve specified the session timeout in web.config file. When the session is timeout I\'m not getting redirect to the login page but I am getting an error saying object refer

Answer 1

Here I am checking session values(two values filled in text box on previous page)

protected void Page_Load(object sender, EventArgs e)
{
    if (Session["sessUnit_code"] == null || Session["sessgrcSerial"] == null)
    {
        Response.Write("");
    }
    else
    {

        lblUnit.Text = Session["sessUnit_code"].ToString();
        LblGrcSr.Text = Session["sessgrcSerial"].ToString();
    }
}