Export DataTable to workbook - excel

Question

i have exported my datatable as shown in the code below. It works fine when exporting the large data but when i try to open the xls file it prompt me this error :
"Excel found unreadable content in filename.xls. Do you want to recover the contents of this workbook? If you trust the source of this workbook, click Yes."
DataTable exportTable = Record.GetAll();
Workbook workbook = new Workbook();
Worksheet sheet = new Worksheet("Test");
for (int x = 0; x < exportTable.Columns.Count; x++)
{
sheet.Cells[0, x] = new Cell(exportTable.Columns[x].ColumnName.ToString());
}
for (int i = 0; i < exportTable.Rows.Count; i++)
{
for (int j = 0; j < exportTable.Columns.Count; j++)
{
sheet.Cells[(i + 1), j] = new Cell(exportTable.Rows[i][j].ToString());
}
}
workbook.Worksheets.Add(sheet);
workbook.Save(#"C:\temp1\Test.xls");
System.IO.FileInfo file = new System.IO.FileInfo(#"C:\temp1\Test.xls");
Response.ClearContent();
Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);
Response.AddHeader("Content-Length", file.Length.ToString());
Response.ContentEncoding = System.Text.Encoding.UTF8;
Response.ContentType = "application/ms-excel";
Response.TransmitFile(file.FullName);
Response.End();

Answer 1

If you are using Excel 2010 or above ( I am not sure about 2007) the file will be saved as XLSX even if you set the extension to XLS. Change the extension to XLSX and it should be fine. Otherwise Excel will detect the difference between the extension and the file structure and will show the message above.