Razor pages - EXT.net v7 - Export to excel Issue

[Geovision]

Dear,

Please note that I encountered an issue when exporting an ext-gridpanel to an excel sheet.
Noting that I am using the ClosedXml library.

Problem Description:
Status Code:200
Status Text:BADRESPONSE: Invalid or unexpected token

   @*-- EXT.net Button*@
   <ext-button text="Export To Excel"  marginAsString="0 0 10 10">
       <listeners>
           <click fn="saveData" />
       </listeners>
   </ext-button>
   

   // Javascript function
 
     function saveData() {
            var data = App.GridPanel1.getRowsValues(
                {
                    prepare: function (data, record) {
                    }
                }),
                columns = App.GridPanel1.getView().getGridColumns(),
                headers = {};

            Ext.each(columns, function (c) {
                headers[c.dataIndex] = c.text.replace(/ /g, "_");
                headers[c.dataIndex] = headers[c.dataIndex].replace(/á/g, "a");
                headers[c.dataIndex] = headers[c.dataIndex].replace(/é/g, "e");
                headers[c.dataIndex] = headers[c.dataIndex].replace(/Ã*/g, "i");
                headers[c.dataIndex] = headers[c.dataIndex].replace(/ó/g, "o");
                headers[c.dataIndex] = headers[c.dataIndex].replace(/ú/g, "u");
                headers[c.dataIndex] = headers[c.dataIndex].replace(/ñ/g, "n");
            });

            Ext.each(data, function (record) {
                for (var field in record) {
                    record[headers[field]] = record[field];
                    delete record[field];
                }
            });

            App.Hidden1.setValue(Ext.encode(data));

            console.log(Hidden1.value.toString());

            App.direct.CallExport(Hidden1.value.toString());

            //App.Hidden1.setValue(Ext.encode(App.GridPanel1.getRowsValues({ selectedOnly: false })));
        };



      // Code behind function

     [Direct]
        public IActionResult OnPostExportToExcel(String JsonFile)
        {

            
                string json = JsonFile;
                XmlNode xml = JsonConvert.DeserializeXmlNode("{\"Row\":" + json + "}", "root");

                DataSet ds = new DataSet();
                DataTable dt = new DataTable();
                System.Xml.XmlReader xmr = new XmlNodeReader(xml);
                ds.ReadXml(xmr);
                if (ds.Tables.Count != 0)
                    dt = ds.Tables[0];

                //  DataTable dt2 = getData();

                using (var workbook = new XLWorkbook())
                {
                    //var worksheet = workbook.Worksheets.Add("Sheet1");
                    var worksheet = workbook.Worksheets.Add(dt);
                    worksheet.TabColor = XLColor.BlueViolet;
                    worksheet.RowHeight = 12;
                    worksheet.ColumnWidth = 20;
                    worksheet.Row(1).Height = 30;
                    worksheet.Row(1).Style.Alignment.Horizontal = XLAlignmentHorizontalValues.Center;
                    worksheet.Row(1).Style.Alignment.Vertical = XLAlignmentVerticalValues.Center;
                    worksheet.Row(1).Style.Fill.PatternType = XLFillPatternValues.Solid;
                    worksheet.Row(1).Style.Fill.SetBackgroundColor(XLColor.Gray);
                    worksheet.Row(1).Style.Alignment.WrapText = true;

                   
                  
                    using (var stream = new MemoryStream())
                    {
                    
                        workbook.SaveAs(stream);
                        var content = stream.ToArray();

                        return File(
                            content,
                           "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
                            "tasktypes.xlsx");
                    }
                }
          
        }//ExportToExcel

in other hand, if you have another suggestions or examples, can you provide it to me? since I tried more than one solution without success.

Thank you.