When you enable formula protection, XLS Padlock can use one of two methods:

- Direct Modification (Recommended): This method modifies formulas directly within the workbook’s source file. It is the default and works reliably in most cases.
- Excel Automation: This method uses automation to control Excel and apply protection.
If the recommended method fails, you can force XLS Padlock to use the automation method by enabling “Use Excel automation for formula protection“. This method is also automatically used for binary workbooks (XLSB) and very large files.
As a last resort, you can activate “Ignore errors when processing the workbook“, but be sure to thoroughly test your compiled application if you enable this option.
