Downloading a file from a link in a GridView inside an UpdatePanel fails

Question

I am trying to save a file (image, word, pdf or any type) in a database via a FileUpload control in asp.net (i.e. file.Docx etc). I then wish to display the file name as a link in a GridView so when the user clicks it, the file will be downloaded.

I have tried everything. In debugging it shows nothing. It reaches the end of Response.End but downloads nothing.

GridView:

<asp:TemplateField>
     <ItemTemplate>
        <asp:LinkButton ID="btnLinkDownloadTender" runat="server" Text='<%#  Eval("UploadedTenderPath") %>'CommandArgument='<%# Eval("UploadedTenderPath") %>' OnClick="DownloadTender"></asp:LinkButton>
     </ItemTemplate>
 </asp:TemplateField>

Upload:

protected void UploadTender()
{
    try
    {
        if (FileUpload1.HasFile)
        {
            string fileName = Path.GetFileName(FileUpload1.FileName);
            FileUpload1.PostedFile.SaveAs(Server.MapPath("~/UploadedTenders/") + fileName);

            HdnFieldUploadedTender.Value = fileName;

            ResultLabel.ResultLabelAttributes("Tender Uploaded", ProjectUserControls.Enums.ResultLabel_Color.Red);
            ResultPanel.Controls.Add(ResultLabel);
        }
        else
        {
            ResultLabel.ResultLabelAttributes("No file specified", ProjectUserControls.Enums.ResultLabel_Color.Red);
            ResultPanel.Controls.Add(ResultLabel);
        }
    } 
}

Download:

protected void DownloadTender(object sender, EventArgs e)
{
    string filePath = (sender as LinkButton).CommandArgument;

    Response.ContentType = ContentType;
    Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath) );
    Response.Write(filePath);
    Response.End();
}

Folder structure:

Answer 1

Try the following, also give us more information about your page. also if you are using chrome check that chrome isn't blocking it

var fileInfo = new FileInfo(filePath);
Response.Clear();
Response.Buffer = true;
Response.AddHeader("Content-Disposition", "attachment; filename=" + fileInfo.Name);
Response.AddHeader("Content-Length", fileInfo.Length.ToString(CultureInfo.InvariantCulture));
Response.ContentType = "application/octet-stream";
Response.BinaryWrite(File.ReadAllBytes(fileInfo.FullName));
Response.Flush();
Response.End();

Edit: In your gridview Row Databound add the following

LinkButton lb = e.Row.FindControl("btnLinkDownloadTender") as LinkButton;
if (lb != null)
     ScriptManager.GetCurrent(this).RegisterPostBackControl(lb);

The above code will register the LinkButton to cause a Full Postback, this will allow the Download to succeed, the same will apply when doing an upload of a file in an Update Panel