Request.QueryString is undefined

Question

i am using the following code to get LogedInUser from LogIn.aspx and send it to Chat.aspx then send it to FrmForAjaxCalls to return data from Db and fill it on div but in running time it telling me in browser console request.querystring is undefined

here is LogIn.aspx code

protected void Button3_Click(object sender, EventArgs e)
{

    Response.Redirect("Chat.aspx?LGN2="+TextBoxUserName.Text);
}

and this is Chat.aspx javascript code

<script type="text/javascript" >
    var xmlhttp;

    function GetData() {
        xmlhttp = null;
        if (window.XMLHttpRequest) {
            xmlhttp = new XMLHttpRequest();
        }
        else if (window.ActiveXObject) {
            xmlhttp = new ActiveXObject();
        }
                  string LogedInUser = Request.Cookies["LogedInUser"].Value;


        var LogedInUser = Request.QueryString["LGN2"];

        xmlhttp.onreadystatechange = function () {

            if (xmlhttp.readystate == 4 || xmlhttp.status == 200) {

                document.getElementById("MyDiv").innerHTML = xmlhttp.responseText;
            }
        }
        xmlhttp.open("GET", "FrmForAjaxCalls.aspx?LGN=" + LogedInUser, true);
        xmlhttp.send();
    }

then i send it to FrmForAjaxCalls to return data but its return nothing on the div with Request.QueryString is undefined exption on browser console

 protected void Page_Load(object sender, EventArgs e)
{
    string LogedInUser = Request.QueryString["LGN2"].ToString();

    StringBuilder html = new StringBuilder();

        String result = String.Empty;
        SqlConnection cnn = new SqlConnection(ConfigurationManager.ConnectionStrings["CRConnection"].ConnectionString);
        SqlCommand cmd = new SqlCommand("Select MessageNum , Message , SenderName ,Date from Message where ReciverUserName='" + LogedInUser + "'", cnn);
        cnn.Open();
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataTable dt = new DataTable();
        da.Fill(dt);
        html.Append("<div id = xxx> ");
        html.Append("<table border='1'>");
        html.Append("<tr>");
        foreach (DataColumn col in dt.Columns)
        {
            html.Append("<th>");
            html.Append(col.ColumnName);
            html.Append("</th>");
        }
        html.Append("</tr>");
        foreach (DataRow row in dt.Rows)
        {
            html.Append("<tr>");
            foreach (DataColumn col in dt.Columns)
            {
                html.Append("<td>");
                html.Append(row[col.ColumnName]);
                html.Append("</td>");
            }
            html.Append("</tr>");
        }
        html.Append("</table>");
        html.Append("</div>");

        Response.Write(html);

}

Answer 1

In your paste for Chat.aspx , you're calling it LGN instead of LGN2 ... Could that be all? In situations like this, your first mission should be to add logging throughout the process to see where it falls apart, so you can pinpoint where the problem is.