Object reference not set to an instance of an object.

Question

Hi
I am trying to check whether the user is logged in or not in Global.asax as shown in code
but I am getting this error
Error: Object reference not set to an instance of an object.

code:

 void Application_BeginRequest(object sender, EventArgs e) 

        

    {

        if (HttpContext.Current.Request.Url.ToString().Contains("SystemUpload"))        

        {

            if (HttpContext.Current.Session["Login"] == null)

            {

                Response.Redirect("~/Login.aspx");

            }

        }

    }

could you kindly suggest me how to fix this issue.

thanks in advance

satish