protected void Button4_Click(object sender, EventArgs e)//导出Excel
    {
        
            Response.Clear();
            Response.Buffer = true;
            Response.Charset = "GB2312";
            Response.AppendHeader("Content-Disposition", "attachment;filename=wasteBook" + DateTime.Now.Date.ToString("yyyyMMdd") + ".xls");
            // 如果设置为 GetEncoding("GB2312");导出的文件将会出现乱码！！！
            Response.ContentEncoding = System.Text.Encoding.UTF7;
            Response.ContentType = "application/ms-excel";//设置输出文件类型为excel文件。
             oStringWriter = new ();
            System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);
            //  turn off paging

            StringWriter sw = new StringWriter();
            HtmlTextWriter htw = new HtmlTextWriter(sw);
            this.GridView1.RenderControl(htw);
            string strHtml = sw.ToString().Trim();
            Response.Output.Write(strHtml);
            Response.Flush();
            Response.End();
            // turn the paging on again

      
   
 // GridView1.AllowPaging = true; //删除不用
  // GridView1.DataBind(); //删除不用

你给出的代码应该不是错误源
但就错误本身而言，一般有两种解决办法：
1. 设置页面指令 EnableEventValidation="false"
2. override Render方法
        protected override void Render(System.Web.UI.HtmlTextWriter writer)
        {
            base.Render(writer);
            this.Page.ClientScript.RegisterForEventValidation(someID);
        }

不知道问题解决没有？我觉得应该还会出现如下错误：　　//重载VerifyRenderingInServerForm方法，否则运行的时候会出现如下错误提示：“类型“GridView”的控件“GridView1”必须放在具有 runat=server 的窗体标记内”
   public override void VerifyRenderingInServerForm(Control control)
    {
        //base.VerifyRenderingInServerForm(control);
    }

不知道问题有没有解决，
试下 在页面改下 <%@ Page Language="C#" EnableEventValidation = "false" AutoEventWireup="true" CodeFile="GridView.aspx.cs" Inherits="GridView" %>
不知道到可以不。