NullReferenceException in creating Excel worksheet

Question

i want to fill an excel file and so i use ExcelPackage: Office Open XML Format . but i have an error. my code:

string fileName = "DBE_BAKIM_FORMU" + ".xlsx";
FileInfo fi = new FileInfo(HttpContext.Current.Server.MapPath("~/") + fileName);

using (ExcelPackage xlPackage = new ExcelPackage(fi))
{
    ExcelWorksheet worksheet = xlPackage.Workbook.Worksheets[1];
    dbeDataContext db = new dbeDataContext();
    CAGRI c = (from x in db.CAGRIs where x.CagriID == ID select x).SingleOrDefault();
    USER u = (from x in db.USERs where x.UserID == Convert.ToInt32(Session["user"]) select x).SingleOrDefault();

    worksheet.Cell(6, 3).Value = c.TalepTarihi.ToShortDateString();
    worksheet.Cell(7, 3).Value = c.TalepTuru;
    worksheet.Cell(8, 3).Value = c.ModulAdi;
    worksheet.Cell(9, 3).Value = c.EkranRaporAdi;
    worksheet.Cell(10, 3).Value = c.VerilenSure;
    worksheet.Cell(11, 4).Value = c.USER.UserName + " " + c.USER.UserSurname;
    worksheet.Cell(12, 4).Value = Convert.ToString(c.USER.UserTel);
    worksheet.Cell(13, 3).Value = c.Aciklama;
    worksheet.Cell(16, 4).Value = u.UserName + " " + u.UserSurname;
    worksheet.Cell(18, 3).Value = Convert.ToString(c.DegerlendirmeTarih);
    worksheet.Cell(19, 3).Value = c.Degerlendirme;
    xlPackage.Save();
}

i have this error in here: xlPackage.Save();

my error says that Object reference not set to an instance of an object.

when i take out xlPackage.Save();, it works and fills in the excel file but it does not save. why am i taking this error?

thanks in advance..

Answer 1

change line 562 of ExcelWorksheet.cs from:

XmlNode pageSetup = _worksheetXml.SelectSingleNode("//d:pageSetup", NameSpaceManager);

to:

XmlNode pageSetup = WorksheetXml.SelectSingleNode("//d:pageSetup", NameSpaceManager);

If the worksheet has not been accessed, calling the public accessor WorksheetXml instead of the private class variable initiallizes it correctly.