Keep Coding

using (XLWorkbook wb = new XLWorkbook())
{
wb.Worksheets.Add(dt);
wb.Style.Alignment.Horizontal = XLAlignmentHorizontalValues.Center;
wb.Style.Font.Bold = true;
Response.Clear();
Response.Buffer = true;
Response.Charset = "";
Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
Response.AddHeader("content-disposition", "attachment;filename= EmployeeReport.xlsx");
using (MemoryStream mymemorystream = new MemoryStream()) {
wb.SaveAs(mymemorystream);
mymemorystream.WriteTo(Response.OutputStream);
Response.Flush();
Response.End();
}
}
The error message I'm getting is
Worksheet names cannot be empty.
How do I solve this?

The returned object of a worksheet adding operation is the worksheet itself. Change the worksheet name on that object:
var ws = wb.Worksheets.Add(dt);
ws.Name = "my sheet name";
Also, because you're using a DataTable as your source for the sheet, you have to make sure the table has a name:
dt.TableName = "my sheet name";
MSDN reference:
https://msdn.microsoft.com/en-us/library/microsoft.office.tools.excel.worksheet.name.aspx?f=255&MSPPError=-2147217396