Asp.net mvc 5 with closedxml. not able to export to excel. getting virus detection message

Question

I am trying to export data to excel using closedxml api but getting virus detected error on export

My code is below

[HttpGet]
        public ActionResult ExportToExcelNew()
        {
            string sheetName = "Report";
            var userClaims = DbAccessWebApiHandler.GetUserClaimAccesshistory(new DateSelection
            {
                StartDate = DateTime.Now.AddDays(-60),
                EndDate = DateTime.Now
            });

            if (userClaims != null)
            {
                DataTable dt = new DataTable();
                dt.Columns.Add("UserName");
                dt.Columns.Add("Email");
                dt.Columns.Add("Claim");
                dt.Columns.Add("AccessedOn");


               foreach (var item in userClaims)
               {
                    dt.Rows.Add(item.UserName, item.Email, item.Claim, item.AccessedOn);
                }
                XLWorkbook wb = new XLWorkbook(XLEventTracking.Disabled);
                var ws = wb.Worksheets.Add(sheetName);
                ws.Cell(2, 1).InsertTable(dt);
                using (var stream = new MemoryStream())
                {
                    wb.SaveAs(stream);
                    stream.Flush();
                   return new FileContentResult(stream.ToArray(),"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
                    {
                        FileDownloadName = "Report.xlsx"
                    };
                }
            }

            return View("Index");
        }

While other simple sort of export works which code looks like

[HttpGet]
        public ActionResult ExportToExcel(DateTime? fromDate, DateTime? toDate)
        {
            if (!fromDate.HasValue) fromDate = DateTime.Now.Date;
            if (!toDate.HasValue) toDate = fromDate.GetValueOrDefault(DateTime.Now.Date).Date.AddDays(1);
            if (toDate < fromDate) toDate = fromDate.GetValueOrDefault(DateTime.Now.Date).Date.AddDays(1);
            ViewBag.fromDate = fromDate;
            ViewBag.toDate = toDate;

            var userClaims = DbAccessWebApiHandler.GetUserClaimAccesshistory(new DateSelection
            {
                StartDate = fromDate.Value,
                EndDate = toDate.Value
            });


            if (userClaims != null)
            {
                var gv = new GridView();

                gv.AutoGenerateColumns = false;
                gv.Columns.Add(new BoundField { HeaderText = "UserName", DataField = "UserName" });
                gv.Columns.Add(new BoundField { HeaderText = "Email", DataField = "Email" });
                gv.Columns.Add(new BoundField { HeaderText = "Accessed", DataField = "Claim" });
                gv.Columns.Add(new BoundField { HeaderText = "Date", DataField = "AccessedOn" });

                var dt = new DataTable();
                dt.Columns.Add("UserName");
                dt.Columns.Add("Email");
                dt.Columns.Add("Claim");
                dt.Columns.Add("AccessedOn");


                foreach (var item in userClaims)
                {
                    dt.Rows.Add(item.UserName, item.Email, item.Claim, item.AccessedOn);
                }

                gv.DataSource = dt;
                gv.DataBind();

                for (var i = 0; i < userClaims.Count; i++)
                {
                    gv.Rows[i].Height = 40;
                }

                Response.ClearContent();
                Response.Buffer = true;
                Response.AddHeader("content-disposition", "attachment; filename=Reports.xls");
                Response.ContentType = "application/ms-excel";
                Response.Charset = "";
                var sw = new StringWriter();
                var htw = new HtmlTextWriter(sw);
                gv.RenderControl(htw);
                Response.Output.Write(sw.ToString());
                Response.Flush();
                Response.End();
            }


            return View("Index");
        }

I have Windows 8.1 OS