How to download pdf file using asp.net?
<p>I upload file and stored in Data folder in server</p>

<p>File path:</p>

<pre><code>Project Name
 |_bin
 |_css
 |_Data
   |_Mohamedfaisal.pdf
</code></pre>

<p>this is my asp.net code</p>

<pre><code>using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using System.Data;

namespace Expatriates {
 public partial class FileUploadForm: System.Web.UI.Page {
  protected void Page_Load(object sender, EventArgs e) {

  }

  protected void Button1_Click(object sender, EventArgs e) {
   if (FileUpload1.HasFile) {
    FileUpload1.PostedFile.SaveAs(Server.MapPath("~/Data/") + FileUpload1.FileName);
   }

   DataTable dt = new DataTable();
   dt.Columns.Add("File", typeof(string));
   dt.Columns.Add("size", typeof(string));
   dt.Columns.Add("type", typeof(string));

   foreach(string strFile in Directory.GetFiles(Server.MapPath("~/Data/"))) {
    FileInfo fi = new FileInfo(strFile);

    dt.Rows.Add(fi.Name, fi.Length, fi.Extension);
   }

   GridView1.DataSource = dt;
   GridView1.DataBind();
  }

  protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e) {
   if (e.CommandName == "Download") {
    Response.Clear();
    Response.Write(e.CommandArgument);
    Response.ContentType = "application/octect-stream";
    Response.AppendHeader("content-disposition", "filename=" + e.CommandArgument);
    Response.TransmitFile(Server.MapPath("~/Data/") + e.CommandArgument); // error occured
    Response.End();
   }
  }
 }
}
</code></pre>

<p>Front End asp.net</p>

<pre><code>&lt;%@ Page Language="C#" AutoEventWireup="true"     CodeBehind="FileUploadForm.aspx.cs" Inherits="Expatriates.FileUploadForm" %&gt;

&lt;!DOCTYPE html&gt;

&lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
&lt;head runat="server"&gt;
    &lt;title&gt;&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
    &lt;form id="form1" runat="server"&gt;
    &lt;div style="font-family:Arial;"&gt;
        &lt;asp:FileUpload ID="FileUpload1" runat="server" /&gt;
        &lt;asp:Button ID="Button1" runat="server" Text="Upload"     OnClick="Button1_Click" /&gt;
        &lt;br /&gt;
        &lt;br /&gt;
        &lt;asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" OnRowCommand="GridView1_RowCommand"&gt;
            &lt;Columns&gt;
                &lt;asp:TemplateField HeaderText="File"&gt;
                    &lt;ItemTemplate&gt;
                        &lt;asp:LinkButton ID="LinkButton1" runat="server" CommandName="Download" Text='&lt;%# Eval("File") %&gt;'&gt;&lt;/asp:LinkButton&gt;
                    &lt;/ItemTemplate&gt;
                &lt;/asp:TemplateField&gt;
                &lt;asp:BoundField DataField="Size" HeaderText="Size in Bytes" /&gt;
                &lt;asp:BoundField DataField="Type" HeaderText="File Type" /&gt;
            &lt;/Columns&gt;
        &lt;/asp:GridView&gt;
    &lt;/div&gt;
    &lt;/form&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>my front end design
<a href="http://i.stack.imgur.com/jiSop.png" rel="nofollow">UI design</a></p>

<p>when I click that link it shows that following error message</p>

<blockquote>
  <p>An exception of type 'System.IO.DirectoryNotFoundException' occurred
  in mscorlib.dll but was not handled in user code</p>
  
  <p>Additional information: Could not find a part of the path 'F:\Visual
  Studio Project\Expatriates\Expatriates\Data\'.</p>
</blockquote>

<p>Uploading file is working perfectly, But I am not getting a download. </p>