Setting up you System 21 Calendars for the New Year
Remember to set up the new calendars in advance, otherwise when the calendars’ expire, everything crashes. These should be set up well in advance because the calendars are required for future transactions such as sales and purchase orders.
Attached is a list of the calendars that require setting up, they are numerous and the ones you need depend on which modules you use and how you have them set them up. For example accounts can be for 4/4/5 weeks and VAT for calendar months.