Created attachment 36722 [details] The template file to be filled We are actually using the 3.15 version, so ignore me if it's fixed already, but: I consistently get this error when trying to remove a certain sheet from the workbook: workbook.removeSheetAt(workbook.getSheetIndex(ExcelExportSheet.STYLES.getName())); But, I only got this after I set up method calls for every single one of the other sheets. Since then - though - even if I remove them the problem pesists.
Please include the stacktrace/error message that you get, a "crash" is a bit unspecific. Also please provide a minimal reproducing test-case or similar code to reproduce the problem.