Presta 1.7.7 - Error while trying to return a product on an order

[OSeudre]

When I try to return a product on an order, with product back in stock checked and creation of a voucher checked, I always have this error :

Une erreur inattendue s'est produite. [PrestaShop\PrestaShop\Core\Domain\Order\Exception\CancelProductFromOrderException code 0]

Stock is correctly updated, but I don't have voucher or credit slip generated. The product is not removed from the order and the total amount is not modified.

Some ideas?

ps: the prestashop was recently updated from 1.7.6.8 to 1.7.7.0