download base file 64 with update panel

Help engineers, I try to download a file that is a Base 64 string; This can be a pdf or image, the case here is that when you want to download the file; in the browser I get the following error

Uncaught TypeError: Can not read property 'PRM_ParserErrorDetails' of undefined     at Sys.WebForms.PageRequestManager._parseDelta (MsAjaxJs? v = c42ygB2U07n37m_Sfa8ZbLGVu4Rr2gsBo7MvUEnJeZ81: 1)     at Sys.WebForms.PageRequestManager._onFormSubmitCompleted (MsAjaxJs? v = c42ygB2U07n37m_Sfa8ZbLGVu4Rr2gsBo7MvUEnJeZ81: 1)     at Array. (MsAjaxJs? V = c42ygB2U07n37m_Sfa8ZbLGVu4Rr2gsBo7MvUEnJeZ81: 1)     at MsAjaxJs? v = c42ygB2U07n37m_Sfa8ZbLGVu4Rr2gsBo7MvUEnJeZ81: 1     at Sys.Net.WebRequest.completed (MsAjaxJs? v = c42ygB2U07n37m_Sfa8ZbLGVu4Rr2gsBo7MvUEnJeZ81: 1)     at XMLHttpRequest._onReadyStateChange (MsAjaxJs? v = c42ygB2U07n37m_Sfa8ZbLGVu4Rr2gsBo7MvUEnJeZ81: 1)

on the side of the aspx I have the following code

            <div class="modal-header " style="align-content: center;">
                <button type="button" class="close" data-dismiss="modal" aria-hidden="true">x</button>
                <h4 class="modal-title">
                    <asp:Label ID="lblTitleModal" ClientIDMode="Static" runat="server">
                                INFORMACION DE LA VENTA
                    </asp:Label>
                </h4>
            </div>

            <div class="modal-body rowsSpaced" style="-ms-align-content: center; -webkit-align-content: center; align-content: center;">
                <div class="form-horizontal">

                    <div class="form-group">
                        <div class="row">
                            <asp:Label ID="lblUsuario" runat="server" Text="USUARIO RESPONSABLE:" CssClass="col-md-3 control-label" AssociatedControlID="txtUsuario"></asp:Label>
                            <div class="col-md-3">
                                <asp:TextBox ID="txtUsuario" runat="server" Style="text-align: center" CssClass="form-control" ReadOnly="True"></asp:TextBox>
                            </div>

                            <asp:Label ID="lblFecha" runat="server" Text="FECHA VENTA:" CssClass="col-md-2 control-label" AssociatedControlID="txtFecha"></asp:Label>
                            <div class="col-md-3">
                                <asp:TextBox ID="txtFecha" runat="server" Style="text-align: center" CssClass="form-control" ReadOnly="True"></asp:TextBox>
                            </div>
                        </div>
                    </div>

                    <div class="form-group">
                        <asp:UpdatePanel ID="upModal" ClientIDMode="Static" runat="server" ChildrenAsTriggers="true">
                            <ContentTemplate>
                                <div class="col-md-4" style="text-align: center;" align="center">
                                    <h4>PAGOS DE LA VENTA</h4>

                                    <asp:RadioButtonList ID="rblLista" ClientIDMode="Static" runat="server">
                                    </asp:RadioButtonList>
                                </div>

                                <div class="col-md-4">
                                    <h4>CARGA DE ARCHIVOS</h4>

                                    <ajaxToolkit:AsyncFileUpload ID="afuArchivoPago" runat="server" ClientIDMode="Static" OnClientUploadStarted="ArchivoUpload" OnClientUploadError="UploadError" OnUploadedComplete="AsyncFileUpload_UploadedComplete" />
                                    <br />
                                    <asp:LinkButton ID="lbArchivoPago" runat="server" ClientIDMode="Static" CssClass="btn btn-primary" Text="GUARDAR PAGO" OnClick="lbArchivoPago_Click"></asp:LinkButton>
                                </div>




                        <div class="col-md-4" style="vertical-align: middle">
                            <h4>DESCARGA DE ARCHIVOS</h4>

                            <asp:LinkButton ID="lbDescargarArchivo" runat="server" ClientIDMode="Static" CssClass="btn btn-success" Text="DESCARGAR PAGO" OnClick="lbDescargarArchivo_Click"></asp:LinkButton>
                        </div>

                                 </ContentTemplate>
                        </asp:UpdatePanel>

                    </div>

                </div>
            </div>

            <div class="modal-footer">
                <button type="button" class="btn btn-primary" data-dismiss="modal" aria-hidden="true">Cerrar</button>
            </div>


        </div>
    </div>
</div>

on the server side is this code

protected void lbDownloadClick_File (object sender, EventArgs e)         {

string Name = null; string Extension = null; byte [] File = null; string Selected = rblLista.SelectedValue; string Base64 = null; string ctype = null;

        using (Data.DatosDataContext db = new Data.DatosDataContext())
        {
            Data.Dat_PagosVenta Pago = db.Dat_PagosVenta.FirstOrDefault(p => p.Id == Convert.ToInt32(Seleccionado));
            Base64 = Pago.Valor;
            Archivo = Convert.FromBase64String(Base64);
            Nombre = Pago.Descripcion;
            Extencion = Pago.Extencion;
            ctype = Pago.ContentType;
        }

        Response.Clear();
        Response.Buffer = true;
        Response.AddHeader("Content-Disposition", "attachment; filename=" + Nombre + "." + Extencion + "");
        Response.ContentType = ctype;
        Response.ContentType = "application/octet-stream";
        //Response.Cache.SetCacheability(HttpCacheability.NoCache);
        //Response.AddHeader("Content-Length", Convert.ToString(Archivo.Length));
        Response.OutputStream.Write(Archivo, 0, Archivo.Length);
        //Response.BinaryWrite(Archivo);
        Response.Flush();
        //Response.End();
        HttpContext.Current.ApplicationInstance.CompleteRequest();
    }

I hope you can help me