Sys.WebForms.PageRequestManagerParserErrorException

Question

我在页面上使用母版页。在这个页面我有更新面板内的gridview。我想将GridView导出到Excel。虽然这样做我得到错误像这样

Sys.WebForms.PageRequestManagerParserErrorException：无法解析从服务器收到的消息。此错误的常见原因是通过调用Response.Write（），响应过滤器，HttpModules或服务器跟踪来修改响应。详细信息：解析附近时出错
Sys.WebForms.PageRequestManagerParserErrorException：无法解析从服务器收到的消息。此错误的常见原因是通过调用Response.Write（），响应过滤器，HttpModules或服务器跟踪来修改响应。

详细信息：解析附近时出错

虽然我添加了以下内容：

EnableEventValidation ="false"

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

我的加价：

<%@ Page Language="C#" MasterPageFile="~/C2SFAMaster.master" AutoEventWireup="false"     EnableEventValidation ="false"   CodeFile="GDNReport.aspx.cs" Inherits="GDNReport" Title="Untitled Page" %>
<%@ Register Assembly="AjaxControlToolkit, Version=1.0.11119.21057, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server"> 
<table>
<tr>
<td>
<TABLE class="TableBgColor">
<TBODY>
<TR class="TableHDColor"><TD colSpan=6>Sample Dispatch Note Report</TD></TR>
<TR>
    <td>Select Fs</td>
    <td>
        <asp:DropDownList ID="cmb_fs" runat="server" Width="200px" AppendDataBoundItems="True" SkinID="DropDowns">
            <asp:ListItem Value="-99">--------------------ALL------------------</asp:ListItem>
        </asp:DropDownList></td>
    <td>DateFrom</td>
    <td>
        <asp:TextBox id="txt_frdate" runat="server" SkinID="Textboxs" />
        <cc1:CalendarExtender id="CalendarExtender1" runat="server" TargetControlID="txt_frdate" Format="d/MM/yyyy" />
    </td>
    <td>DateTo</td>
    <td>
        <asp:TextBox id="txt_todate" runat="server" SkinID="Textboxs" />
        <cc1:CalendarExtender id="CalendarExtender2" runat="server" TargetControlID="txt_todate" Format="d/MM/yyyy" />
    </td>
</TR></TABLE> 
</td>
</tr>
<tr>
    <td align ="center" >
        <asp:Button ID="btn_view" runat="server" Text="View" OnClick="btn_view_Click" OnClientClick="return viewcheck();" CssClass="Button" />
    </td>
</tr>
<tr>
<td align="center"> 
    <asp:UpdatePanel id="swpnl" runat="server" UpdateMode="Conditional">
        <ContentTemplate>
            <asp:GridView ID="gdview" runat="server" OnRowDataBound="gdview_RowDataBound"    OnRowCreated="gdview_RowCreated" style="position: relative" />
        </ContentTemplate>
        <triggers>
            <asp:AsyncPostBackTrigger ControlID="btn_view" EventName="Click">    </asp:AsyncPostBackTrigger>
            <asp:AsyncPostBackTrigger ControlID="btn_export" EventName="Click" />
        </triggers>
    </asp:UpdatePanel>
    <asp:Button ID="btn_export" runat="server" CssClass="Button" OnClick="btn_export_Click" Style="position: relative" Text="Export To Excel" />    
</td></tr>
</table>
</asp:Content>