Ajax加载下在进度,消息: Sys.WebForms.PageRequestManagerParserErrorException: 无法分析从服务器收到的消

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta content="IE=EmulateIE7" http-equiv="X-UA-Compatible">

<title>Untitled Page</title>

</head>

<body>

<form id="MyForm" runat="server"><div id="Main">



<div id="NowMenu">

    <div id="NowButton">

<asp:ScriptManager ID="ScriptManager1" runat="server" />

<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">

    <ContentTemplate>   

        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Loading" />

        <asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="Loading" /> 

    </ContentTemplate>

    <Triggers>

         <asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />

         <asp:AsyncPostBackTrigger ControlID="Button2" EventName="Click" />

    </Triggers>

</asp:UpdatePanel>

    </div>

</div>

<asp:UpdateProgress ID="UpdateProgress2" runat="server" AssociatedUpdatePanelID="UpdatePanel1">

    <ProgressTemplate>

        <div id="loader_container">

	        <div id="loader">

		         <div style="text-align:center;"><img alt="loading" style=" vertical-align:middle; margin-right:8px;" src="/Template/Image/loading.gif" />数据载入中，请稍后……</div>

		         <div id="loader_bg"><div id="progress"></div></div>

	        </div>

        </div>

    </ProgressTemplate>

</asp:UpdateProgress> 



</div>

</form>  

</body>

</html>

protected void Button1_Click(object sender, EventArgs e)

        {

            System.Threading.Thread.Sleep(3000);

        }



        public void Button2_Click(object sender, EventArgs e)

        {

            string Sql = " Where [StatUs]=0 And [State] !='D' And [Position] = 'C' ";

            GetContent(Sql, DateTime.Now.AddDays(-1).ToString("yyyyMMdd"));

        }



/// <summary>

        /// 下载文件，文件名重写，以数据流形式写入

        /// </summary>

        /// <param name="FileName">文件名</param>

        /// <param name="FileContent">文件内容</param>

        /// <returns>无</returns>

        public static void DownloadExport(string FileName, string FileContent)

        {

            byte[] txtcontent = Encoding.Default.GetBytes(FileContent);

            try

            {

                HttpContext.Current.Response.Clear();

                HttpContext.Current.Response.Charset = "utf-8";

                HttpContext.Current.Response.Buffer = false;

                HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.UTF8;

                HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(System.Text.Encoding.UTF8.GetBytes(FileName)));

                HttpContext.Current.Response.AppendHeader("Content-Length", txtcontent.Length.ToString());

                HttpContext.Current.Response.ContentType = "application/octet-stream";

                HttpContext.Current.Response.BinaryWrite(txtcontent);

                HttpContext.Current.Response.Flush();

                HttpContext.Current.Response.Close();

                HttpContext.Current.Response.End();

            }

            catch (Exception ex)

            {

                throw (ex);

            }

            finally

            {

                txtcontent.Clone();

            }

        }

点击按钮会出现加载数据的层,可是结束后报错:
网页错误详细信息

消息: Sys.WebForms.PageRequestManagerParserErrorException: 无法分析从服务器收到的消息。之所以出现此错误，常见的原因是: 在通过调用 Response.Write() 修改响应时，将启用响应筛选器、HttpModule 或服务器跟踪。
详细信息: 分析附近的“====================”时出错。
行: 4723
字符: 21
代码: 0
URI: http://172.18.254.125:808/ScriptResource.axd?d=

请高手指点如何解决!!