UpdatePanel无法导出下载文件

protected void Page_Load(object sender, EventArgs e)
{ 
    ScriptManager sm = Page.Master.FindControl("ScriptManager1") as ScriptManager;
    if (sm != null)
    {
        foreach (GridViewRow item in gvInvoiceHistory.Rows)
        {
            LinkButton lbtnTemp = item.FindControl("btnInvoiceNumber") as LinkButton;
            if (lbtnTemp != null)
            {
                sm.RegisterPostBackControl(lbtnTemp);
            }
        }
    }  
}

protected void btnInvoiceNumber_OnClick(object sender, EventArgs e)
{
    LinkButton btnTemp = sender as LinkButton;
    if (btnTemp != null)
    {
        var path = ConfigurationManager.AppSettings["InvoicePdfPath"];
        var fileName = btnTemp.Text.Trim() + ".pdf";
        if (!FileHandler.DownLoadFile(path, fileName))
        {
            var msg = GetLocalResourceObject("InvoiceIsNotAvailable").ToString();
            ScriptManager.RegisterStartupScript(upMain, upMain.Page.GetType(), "DownLoadFile", string.Format("alert('{0}');", msg), true);
 
            //如果不存在就跳转，参见 http://www.cnblogs.com/vipsoft/p/3627683.html
　　　　　　//string url = "http://www.vipsoft.com.cn";
　　　　　　//ResponseRedirect.Redirect(Response, url, "_blank", "'toolbar=0,scrollbars=1,status=0,menubar=0,resizable=1,top=0,left=0,height=800,width=1000");}



        }
    }
}

//Updatepanel 会有异常 参考下面的链接查看下载方法
public static bool DownLoadFile(string path,string fileName)
{
    bool result = false;
    string filePath = HttpContext.Current.Server.MapPath(path + fileName);
    if (File.Exists(filePath))
    {
        FileInfo fileInfo = new FileInfo(filePath);
        HttpContext.Current.Response.Clear();
        HttpContext.Current.Response.ClearContent();
        HttpContext.Current.Response.ClearHeaders();
        HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);
        HttpContext.Current.Response.AddHeader("Content-Length", fileInfo.Length.ToString());
        HttpContext.Current.Response.AddHeader("Content-Transfer-Encoding", "binary");
        HttpContext.Current.Response.ContentType = "application/octet-stream";
        HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("utf-8");
        HttpContext.Current.Response.WriteFile(fileInfo.FullName);
        HttpContext.Current.Response.Flush();
        HttpContext.Current.Response.End();
        result = true;
    }
    return result;
}

ScriptManager1 放在 MasterPage中，查找 ScriptManager1 时，
Page.Master.FindControl("ScriptManager1") as ScriptManager;

FileHandler文件下载：http://www.cnblogs.com/vipsoft/p/3521958.html

如果不存在就跳转，参见 http://www.cnblogs.com/vipsoft/p/3627683.html