FAQ Q368: When entering a winter season, why am I getting the error: End date/time must be after start date/time?
Sezione: Determining availability and booking constraints
You will need to enter two seasons with the exact same settings: One starting on your chosen date and ending on December 31st and then another one starting on January 1st and ending on the chosen date. Both seasons can be defined for a specific year or can be recurring each year (winter).