Code:
protected void btn_Edit_Click(object sender, EventArgs e)
    {
        Panel1.Visible = true;
        Button5.Visible = true;
        if (FileUpload1.HasFile)
        {
            //string filename = Path.GetFileName(FileUpload1.PostedFile.FileName);
            //FileUpload1.SaveAs(Server.MapPath(filename));
            string filename = "~/Uploads/" + FileUpload1.FileName;
...