XLSX Export is giving error when table have more than 7 groups in Birt ?

Migrateduser

Hi,

I have design a report in Birt having 8 groups on a table, it is working fine when i am exporting it to PDF & Excel,
but it giving error when i am exporting it to XLSX.

when i am testing the same report with 7 groups then it is working fine for all - pdf ,xls, xlsx.

Is there any solution to resolve this issue ?