I'd recommend using a library which doesn't depend on the user having the correct version of Excel installed. For example:
GitHub - JanKallman/EPPlus: Create advanced Excel spreadsheets using .NET[
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result = DB.GetReport(Session, out rowcount, out records, User, (int)process, DateTime.Now.AddMonths(-3), DateTime.Now);
using (var package = new ExcelPackage())
{
var sheet = package.Workbook.Worksheets.Add("Report");
sheet.Cells["A1"].LoadFromDataTable(records, true, TableStyles.Medium9);
package.SaveAs(filePath);
}