An error of type E_ERROR was caused in line 131 of the file /public_html/wp-content/plugins/atum-multi-inventory/classes/Notifications/SalesNotifications.php. Error message: Uncaught Error: Class 'AtumMultiInventory\Notifications\Helpers' not found in /public_html/wp-content/plugins/atum-multi-inventory/classes/Notifications/SalesNotifications.php:131
It happens when the order is paid, causing a failure in sending the order confirmation email.
Some of the customers saw that failure page and refreshed the page several times which caused duplicated payments and orders.
This issue has occurred since the last update.