webform 导出excel时报错

webform导出excel时出现错误：Sys.WebForms.PageRequestManagerParserErrorException:The message received from the server could not be parsed.Common causes for this error are when the response is modified by calls to Response.Write(),response filters,HttpModules, or server trace is enabled.
details: error parsing near 

//从服务器上下载导出的excel

public void down(string filename)

{

string FilePath = Server.MapPath("~") ;
        Response.Clear();
        Response.ContentType = "application/ms-excel";
        Response.AddHeader("Content-Disposition", "attachment;FileName=" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8));
        Response.WriteFile(FilePath + filename);
        Response.Flush();
        Response.End();

}

在response.end()时出现的错误

一般是因为使用了ajax控件造成的,处理方法如下：

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

<Triggers>
                <asp:PostBackTrigger ControlID="btnExcel" />
            </Triggers>
</asp:UpdatePanel>