How to fix this error in Microsoft Excel: "Excel fount unreadable content in '<fileName>.xlsm'. Do you want to recover the contents of this workbook?"

Hi,

This is due to the default installation of Office didn't include VBA, and with the enhanced security features of Office in this configuration, any macros are seen as unreadable and therefore removed for your protection.

The solution is to install VBA in Office (as well as making sure you have the "Trust Center" settings set to either allow macros or at least prompt you to enable/disable).