Fatal error: Uncaught Error: Interface "Sabre\Xml\XmlSerializable" not found in /var/www/html/src/vendor/num-num/ubl-invoice/src/SettlementPeriod.php:27 Stack trace: #0 {main} thrown in /var/www/html/src/vendor/num-num/ubl-invoice/src/SettlementPeriod.php on line 27