I want to send datatable value from one page to 2nd in asp.net c#

Question

I have a web project in which a 'Cart.aspx page'. In this page i stored datatable value in session variable like below:

 

" Session["Buyitem"]=dt; . Now i want to use this session variable value in second page 'PaymentGateway.aspx' page like below:

DataTable dt;
dt = (DataTable)Session["Buyitem"];
for (int i = 0; i <= dt.Rows.Count - 1; i++)
{
con = new SqlConnection(cons);
con.Open();
string sql = ("Insert into OrderDetails(OrderID,ProductName,ProductImage,Price,CustomerName,BillingAddress,OrderDate,OrderStatus)values('" + Session["OrderID"] + "','" + dt.Rows[i]["Product_Name"] + "','" + dt.Rows[i]["ProdImage"] + "','" + dt.Rows[i]["ProdPrice"] + "','" + Session["CstmrName"] + "','" + Session["BillingAddress"] + "','" + Session["Orderdate"] + "','Pending')");
cmd = new SqlCommand(sql, con);
cmd.ExecuteNonQuery();
con.Close();
Session["Buyitem"] = null;
}

but i am getting "System.NullReferenceException: 'Object reference not set to an instance of an object.'

dt was null."

 

Now i want to clear something:

 

By Cart.aspx page we redirected to Paytm gateway page and on successfull payment then redirected to PaymentGateway.aspx page .

 

Cart.aspx page------------------->Paytm Gateway Page-------------------------> PaymentGateway.aspx

 

Plz Help..

Thanks