使用 c# 和 asp.net 将 HTML 内容转换为 Pdf

在这里，我试图将htmldiv标签中的内容转换为pdf，我发现了以下错误：

Input string was not in a correct format is occur

这是我尝试使用 c# 的代码：

    divexcel.Visible = true;
    Response.ContentType = "application/pdf";
    Response.AddHeader("content-disposition", "attachment;filename=TestPage.pdf");
    Response.Cache.SetCacheability(HttpCacheability.NoCache);
    StringWriter sw = new StringWriter();
    HtmlTextWriter hw = new HtmlTextWriter(sw);
    divexcel.RenderControl(hw);
    StringReader sr = new StringReader(sw.ToString());
    Document pdfDoc = new Document(PageSize.A4, 80f, 80f, -2f, 35f);
    HTMLWorker htmlparser = new HTMLWorker(pdfDoc);
    PdfWriter writer = PdfWriter.GetInstance(pdfDoc, Response.OutputStream);
    pdfDoc.Open();
    //head.WriteSelectedRows(0, -1, page.Width / 8, page.Height - pdfDoc.TopMargin + head.TotalHeight, writer.DirectContent);
    //pdfDoc.Add(headerTbl);   
    htmlparser.Parse(sr);
    pdfDoc.Close();
    Response.Write(pdfDoc);
    Response.End();
------------------------------------------

这是我的 html 代码

<div id="divexcel" runat="server">
    <table id="tbDetails" width="800px">
    <thead >
    <tr>
    <td></td>
    <td></td>
    <td></td>
    </tr>
    </thead>
    <tbody>
    </tbody>
    </table>
    </div>