How to fix 0x800a138f - Microsoft JScrip runtime error: `Sys.Extended.UI` is null or not an object

<%@ Page Title="UplaodFile" Language="VB" MasterPageFile="~/MasterPage.Master" AutoEventWireup="true" codefile="Upload.aspx.vb" Inherits="Project_Slan.AjaxFileUpload"%>
<%@ Register assembly="AjaxControlToolkit" namespace="AjaxControlToolkit" tagprefix="asp" %>

<asp:Content runat="server" ID="FeaturedContent" ContentPlaceHolderID="FeaturedContent">
    <section class="featured">
        <div class="content-wrapper">
            <hgroup class="title">
            </hgroup>
 
        </div>
    </section>

</asp:Content>
<asp:Content runat="server" ID="BodyContent" ContentPlaceHolderID="MainContent">

   <h3>Ajax FileUpload</h3>
    
    
    <asp:AjaxFileUpload ID="AjaxFileUpload1" runat="server"
        OnUploadComplete="AjaxFileUploadEvent" Width="500px" />

    
</asp:Content>
<asp:Content ID="Content1" runat="server" contentplaceholderid="HeadContent">
</asp:Content>

Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports AjaxControlToolkit

Namespace Project_Slan
    Partial Public Class AjaxFileUpload
        Inherits System.Web.UI.Page
        Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)

        End Sub

        Protected Sub AjaxFileUploadEvent(ByVal sender As Object, ByVal e As AjaxFileUploadEventArgs)
            Dim filename As String = System.IO.Path.GetFileName(e.FileName)
            Dim strUploadPath As String = "~/uploads/"
            AjaxFileUpload1.SaveAs(Server.MapPath(strUploadPath) + filename)
        End Sub

    End Class

End Namespace 

<form id="masterform1"  runat="server">
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        <Scripts>
            <asp:ScriptReference Name="MsAjaxBundle" />
            <asp:ScriptReference Name="jquery" />
            <asp:ScriptReference Name="jquery.ui.combined" />
            <asp:ScriptReference Name="WebForms.js" Assembly="System.Web" Path="~/Scripts/WebForms/WebForms.js" />
            <asp:ScriptReference Name="WebUIValidation.js" Assembly="System.Web" Path="~/Scripts/WebForms/WebUIValidation.js" />
            <asp:ScriptReference Name="MenuStandards.js" Assembly="System.Web" Path="~/Scripts/WebForms/MenuStandards.js" />
            <asp:ScriptReference Name="GridView.js" Assembly="System.Web" Path="~/Scripts/WebForms/GridView.js" />
            <asp:ScriptReference Name="DetailsView.js" Assembly="System.Web" Path="~/Scripts/WebForms/DetailsView.js" />
            <asp:ScriptReference Name="TreeView.js" Assembly="System.Web" Path="~/Scripts/WebForms/TreeView.js" />
            <asp:ScriptReference Name="WebParts.js" Assembly="System.Web" Path="~/Scripts/WebForms/WebParts.js" />
            <asp:ScriptReference Name="Focus.js" Assembly="System.Web" Path="~/Scripts/WebForms/Focus.js" />
            <asp:ScriptReference Name="WebFormsBundle" />
    </scripts>
</asp:scriptManager>