There is an Error in the odoo source code (or was, i do not know if it has been fixed in the mean time since i have encountered this.)

This code snippet from the loyalty module basically triggers the warning and needs improvement, is the problem still occuring?

@api.onchange('expiration_date') 

def _restrict_expiration_on_loyalty(self):

 for card in self: if card.program_type == 'loyalty: 

raise ValidationError(_("Expiration date cannot be set on a loyalty card."))