JavaScript runtime error: Sys.WebForms.PageRequestManagerParserErrorException

HI.

I am using VS 2010, C# and ASP.NET Web Application.

I am trying to export dataset to excel. I am getting an error as - JavaScript runtime error: Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed.

The excel is not created. I have used the below code:

 DataSet ds = getDataSetExportToExcel(con);
                    using (XLWorkbook wb = new XLWorkbook())
                    {
                        wb.Worksheets.Add(ds);

                        Response.Clear();
                        Response.Buffer = true;
                        Response.Charset = "";
                        Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                        Response.AddHeader("content-disposition", "attachment;filename= " + filename1 + ".xlsx");
                        using (MemoryStream MyMemoryStream = new MemoryStream())
                        {
                            wb.SaveAs(MyMemoryStream);
                            MyMemoryStream.WriteTo(Response.OutputStream);

                            Response.Flush();
                            Response.End();
                        }
                    }

The error is at line - Response.End()

I have the scriptmanager added in the page with the below code:

<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true" AsyncPostBackTimeout="360000"></asp:ScriptManager><asp:UpdatePanel ID="upd1" runat="server"><ContentTemplate>

How to fix this?

Thanks