Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
Source Error:
| An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. | 
Stack Trace:
| 
             | 
Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1
Code:
Default.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<%@ Register Src="WebUserControl.ascx" TagName="WebUserControl" TagPrefix="uc1" %>
<%@ Register TagPrefix="telerik" Namespace="Telerik.Web.UI" Assembly="Telerik.Web.UI" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <telerik:RadScriptManager ID="RadScriptManager1" runat="server" />
        <telerik:RadAjaxManager ID="RadAjaxManager1" runat="server">
        </telerik:RadAjaxManager>
        <uc1:WebUserControl ID="WebUserControl1" runat="server" />
    </form>
</body>
</html>
Default.aspx.cs:
using System;
public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
    }
}
WebUSerControl.acsx:
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="WebUserControl.ascx.cs" Inherits="WebUserControl" %>
<%@ Register TagPrefix="telerik" Namespace="Telerik.Web.UI" Assembly="Telerik.Web.UI" %>
<telerik:RadAjaxManagerProxy ID="AjaxManagerProxy1" runat="server">
    <AjaxSettings>
    <telerik:AjaxSetting AjaxControlID="OrdersGrid">
            <UpdatedControls>
                <telerik:AjaxUpdatedControl ControlID="OrdersGrid" />
            </UpdatedControls>
        </telerik:AjaxSetting>
        <telerik:AjaxSetting AjaxControlID="EmployeesGrid">
            <UpdatedControls>
                <telerik:AjaxUpdatedControl ControlID="RadTabStrip1" />
                <telerik:AjaxUpdatedControl ControlID="RadMultiPage1" LoadingPanelID="RadAjaxLoadingPanel1" />
                <telerik:AjaxUpdatedControl ControlID="EmployeesGrid" />
            </UpdatedControls>
        </telerik:AjaxSetting>
        
    </AjaxSettings>
 
</telerik:RadAjaxManagerProxy>
<telerik:RadAjaxLoadingPanel ID="RadAjaxLoadingPanel1" runat="server" />
<telerik:RadGrid ID="EmployeesGrid"  runat="server" AutoGenerateColumns="true"
    AllowSorting="True" AllowMultiRowSelection="False" AllowPaging="True" PageSize="5"
    GridLines="None" ShowStatusBar="true" style="margin-bottom: 20px;">
    <PagerStyle Mode="NumericPages"></PagerStyle>
    <ClientSettings EnablePostBackOnRowClick="true">
        <Selecting AllowRowSelect="true" />
    </ClientSettings>
</telerik:RadGrid>
<telerik:RadTabStrip runat="server" ID="RadTabStrip1" MultiPageID="RadMultiPage1"
    SelectedIndex="0">
    <Tabs>
        <telerik:RadTab runat="server" Text="Sanjay" PageViewID="PageView1" />
        <telerik:RadTab runat="server" Text="Sanjay" PageViewID="PageView2" />
    </Tabs>
</telerik:RadTabStrip>
<telerik:RadMultiPage runat="server" ID="RadMultiPage1" SelectedIndex="0" RenderSelectedPageOnly="false">
    <telerik:RadPageView runat="server" ID="PageView1"> 
    <telerik:RadGrid ID="RadGrid1"  runat="server" AutoGenerateColumns="true"
    AllowSorting="True" AllowMultiRowSelection="False" AllowPaging="True" PageSize="5"
    GridLines="None" ShowStatusBar="true" style="margin-bottom: 20px;">
    <PagerStyle Mode="NumericPages"></PagerStyle>
    <ClientSettings EnablePostBackOnRowClick="true">
        <Selecting AllowRowSelect="true" />
    </ClientSettings>
</telerik:RadGrid>
    
    </telerik:RadPageView>
    <telerik:RadPageView>
    <telerik:RadGrid ID="RadGrid2"  runat="server" AutoGenerateColumns="true"
    AllowSorting="True" AllowMultiRowSelection="False" AllowPaging="True" PageSize="5"
    GridLines="None" ShowStatusBar="true" style="margin-bottom: 20px;">
    <PagerStyle Mode="NumericPages"></PagerStyle>
    <ClientSettings EnablePostBackOnRowClick="true">
        <Selecting AllowRowSelect="true" />
    </ClientSettings>
</telerik:RadGrid>
    
    </telerik:RadPageView>
      </telerik:RadMultiPage>
WebUserControl.acxs.cs:
using System;
using System.Data;
public partial class WebUserControl : System.Web.UI.UserControl
{
    protected void Page_Load(object sender, EventArgs e)
    {
        DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("Contract Number", typeof(string)));
dt.Columns.Add(new DataColumn("Customer Name", typeof(string)));
DataRow dr = dt.NewRow();
        dr["Customer Name"] = "Sanjay";  
        dr["Contract Number"] = "Sanjay"; 
dt.Rows.Add(dr);
        EmployeesGrid.DataSource = dt;
        EmployeesGrid.DataBind();
        
    }
}
