Created Unassigned: Excel Export can not be saved any more 4.0.0.1! [15053]

Hello friends,

I am trying to use EPPlus 4.0 beta to generate an Excel worksheet,
but I recieve always the following error:

The CPF database has been loaded.
The Excel-Export has started.
Der Objektverweis wurde nicht auf eine Objektinstanz festgelegt..
Error saving file D:\Daten\SerienImportExport\Trail-Export-021.xlsxError saving file D:\Daten\SerienImportExport\Trail-Export-021.xlsx

Do you have any advice. We try to write a large amount of rows to the Excel worksheet.

There was a System.OutOfMemory exception before. We have tried to upgrade to 4.0.0.1
and know we receive this error. Please any help will be greatly appreciated.

Best regards

Kurt