<asp:GridView ShowHeader="false" AutoGenerateColumns="false" DataSource='<%#Bind("exb") %>'
                                ID="GridView5" DataKeyNames="ID" runat="server" Width="100%" >

    private DataTable exb;
    public DataTable Exb
    {
        get
        {
            return exb;
        }
        set
        {
            exb = value;
        }
    }

    public class EditTourCard
    {
        public void UpdateData(TC data)
        {
            data.UpdateTС();
        }
}

    public void UpdateTС()
    {
        foreach (DataRow dr in exb .Rows)
        {
        System.Web.HttpContext.Current.Response.Write(dr["Active"].ToString());
        }
        
    }

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

<asp:ObjectDataSource ID="ObjectDataSource1" runat="server" DataObjectTypeName="TC"
    SelectMethod="GetData" TypeName="EditTC" UpdateMethod="UpdateData" OnUpdating="update_event">
    </asp:ObjectDataSource>

System.Web.HttpContext.Current.Response.Write(dr["Active"].ToString());