You have exceeded the API rate limit. Implement exponential backoff in your retry logic and monitor request volumes.

Errors return HTTP status codes (e.g., 400 Bad Request, 500 Internal Server Error) and a JSON body with a standardized code (e.g., 111: INVALID SECURE HASH). Full codes are in Section 5.0 of the documentation.

Bulk operations (BULK_INTERBANK_PAYMENT, BULK_DOMESTIC_PAYMENT) process transactions sequentially. Responses confirm receipt but not final status—use transaction reference numbers for follow-up