Incident Summary: 

We experienced an issue affecting some customer-initiated transactions processed through the Adyen payment gateway. The problem was identified within the temporary token workflow after a recent upgrade to our payment integration. The issue was directly linked to the transition from Adyen's Classic integration to the Checkout integration. As a result, certain transactions were failing due to unsupported flows in the new integration. After identifying the problem, we reverted the changes, and transaction processing has since returned to normal.

Services Impacted:

Customer transactions processed via the Adyen payment gateway, specifically those involving the temporary (CSE) token workflow, were impacted.

Root Cause:

The root cause of the issue was the transition from Adyen's Classic Integration to the Checkout Integration executed on Aug 15th,2024. During this upgrade, we discovered that one of Adyen's existing payment flows, specifically the process of converting a temporary (CSE) token into a permanent token, was not supported in the Checkout integration. This incompatibility between the old and new integration flows led to the failure of some customer transactions, resulting in 4xx errors occurring during payment processing.

While we had monitoring systems in place for server-side 5xx errors, we lacked appropriate alerts for 4xx errors, which delayed our identification and resolution of the issue.

Remediation & Follow-up Steps:

To resolve the issue, we reverted to the previous integration, which immediately restored normal transaction processing. We also implemented new alerts to quickly detect and address similar issues in the future.

Looking ahead, we have added automated tests to cover the scenarios that led to this issue, ensuring they are included in future testing cycles. Additionally, we are working closely with Adyen to find an alternative solution for the unsupported CSE token workflow in the Checkout Integration. Once a viable solution is identified, we will proceed with implementing the necessary changes.