diff --git a/invoice.py b/invoice.py index d8d764192d..7866be3048 100644 --- a/invoice.py +++ b/invoice.py @@ -63,7 +63,11 @@ class Invoice(metaclass=PoolMeta): if amount < 0: line = self._get_deposit_recall_invoice_line( amount, account, description) - line.sequence = max(l.sequence for l in self.lines) + try: + line.sequence = max(l.sequence for l in self.lines + if l.sequence is not None) + except ValueError: + pass line.save() if to_delete: InvoiceLine.delete(to_delete)