Cannot access a disposed object. Object name: 'System.Net.Sockets.NetworkStream'

        string strConn = ConfigurationManager.ConnectionStrings["Connection"].ConnectionString.ToString();
        SqlConnection con = new SqlConnection(strConn);

        FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftpserver");

        request.Credentials = new NetworkCredential("username", "pass");

        FtpWebResponse response = (FtpWebResponse)request.GetResponse();
        Stream responsestream = response.GetResponseStream();
        StreamReader sr = new StreamReader(responsestream);
        SqlBulkCopy bc = new SqlBulkCopy(con.ConnectionString, SqlBulkCopyOptions.TableLock);
        try
        {
            string line = sr.ReadLine();
            string[] value = line.Split(',');
            DataTable dt = new DataTable();
            DataRow row;
            foreach (string dc in value)
            {
                dt.Columns.Add(new DataColumn(dc));
            }

            while (!sr.EndOfStream)
            {
                value = sr.ReadLine().Split(',');
                if (value.Length == dt.Columns.Count)
                {
                    row = dt.NewRow();
                    row.ItemArray = value;
                    dt.Rows.Add(row);
                }
            }


            bc.DestinationTableName = "CSVTest";
            bc.BatchSize = dt.Rows.Count;
            con.Open();
            bc.WriteToServer(dt);

            //File.Open(str1, FileMode.Open, FileAccess.Read, FileShare.None);
            using (var writer = new StreamWriter(responsestream))
            {
                writer.Write("");
            }
        }
        catch (ObjectDisposedException a)
        {
            Console.WriteLine("Caught: {0}", a.Message);
        }
        finally
        {
            //Closing Bulk Copy
            bc.Close();
            //Closing Sql Connection
            con.Close();
            //Dispose method internally calls Close..So you dont need to call the close explicitly.
            sr.Dispose();
        }

read file from ftp sever complete read file while loop thorws error Cannot access a disposed object. Object name: 'System.Net.Sockets.NetworkStream'.