title: 0x8000000a - JavaScript runtime error: The data necessary to complete this operation is not yet available
body: <p>I have been experiencing the error (in the title) and have been trying to find an answer. The best one so far is <a href="https://stackoverflow.com/questions/1038305/ajax-error-the-data-necessary-to-complete-this-operation-is-unavailable">AJAX Error: The data necessary to complete this operation is unavailable</a>.</p>
  
  <p>However, in that case, the OP was specifically using jQuery/Ajax, but I am using the AjaxControlToolkit and I am not sure how to implement the answer and was hoping someone may be able to help.</p>
  
  <p>FYI: In most of the questions on the subject all say that the problem does not exist in Chrome/Firefox etc. (and it does when I try), but I am using IE (as its company policy) and am running IE 10 on Windows 8, using Visual Studio 2013</p>
  
  <p>EDIT - Added code.</p>
  
  <p>Very simple, but gives the error.</p>
  
  <blockquote>
    <p>Webform1.aspx</p>
  </blockquote>
  
  <pre><code>&lt;%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="HotTransferBags.WebForm1" %&gt;
  
  &lt;%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %&gt;
  
  &lt;!DOCTYPE html&gt;
  
  &lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
  &lt;head runat="server"&gt;
      &lt;title&gt;&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;form id="form1" runat="server"&gt;
      &lt;div&gt;
          &lt;asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server"&gt;&lt;/asp:ToolkitScriptManager&gt;
          &lt;asp:UpdatePanel ID="UpdatePanel1" runat="server"&gt;
              &lt;ContentTemplate&gt;
                  &lt;asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged"&gt;
                      &lt;asp:ListItem Text="Item 1" Value="1" /&gt;
                      &lt;asp:ListItem Text="Item 2" Value="2" /&gt;
                      &lt;asp:ListItem Text="Item 3" Value="3" /&gt;
                      &lt;asp:ListItem Text="Item 4" Value="4" /&gt;
                      &lt;asp:ListItem Text="Item 5" Value="5" /&gt;
                  &lt;/asp:DropDownList&gt;
  
                  &lt;asp:TextBox runat="server" ID="TextBox1" /&gt;
              &lt;/ContentTemplate&gt;
          &lt;/asp:UpdatePanel&gt;
      &lt;/div&gt;
      &lt;/form&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <blockquote>
    <p>Code Behind - Webform1.aspx.cs</p>
  </blockquote>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Web;
  using System.Web.UI;
  using System.Web.UI.WebControls;
  
  namespace HotTransferBags
  {
      public partial class WebForm1 : System.Web.UI.Page
      {
          protected void Page_Load(object sender, EventArgs e)
          {
  
          }
  
          protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
          {
              TextBox1.Text = "You selected " + DropDownList1.SelectedItem.Text;
          }
      }
  }
  </code></pre>
  
  <blockquote>
    <p>Error reported in Visual Studio...</p>
  </blockquote>
  
  <p>As this is a simple form, only one error is reported, but my full application lists about 20 of them</p>
  
  <p><img src="https://i.stack.imgur.com/QOcyM.jpg" alt="JavaScript Error in Visual Studio Error List Window"></p>