In order to cancel or change an order for split scenarios, our gateway requires a cart object. However, if the checkout process via OMS sends a null/unknown cart object, our gateway cannot process these operations, resulting in a parsing error from the Newtonsoft library used in the gateway.

To replicate the issue, update the cart object in the /transaction entity with a null value using our API for sending additional data. https://developers.vtex.com/docs/api-reference/payments-gateway-api#post-/api/pvt/transactions/-transactionId-/additional-data

If the initial cart object is no longer available, retrieving it and sending it back to the /transaction entity using our API for sending additional data can be a challenging process. If this is the case, please reach out to the VTEX support team for assistance.