Hi Patrick,
Thank you very much for your interest in Syncfusion Products.
To avoid throwing error when unknown named ranges were parsed, please set the "ThrowOnUnknownNames" property as false.
Following code snippet illustrates this:
workbook.ThrowOnUnknownNames = false;
Please go through the following online documentation link for more details.
http://help.syncfusion.com/ug_94/Reporting/XlsIO/Windows%20Forms/default.htm?turl=Documents%2Fworkbook.htmPlease let me know if you have any concern.
Regards,
Manojkumar.