Idempotency Keys on All Write Endpoints

Every POST, PUT, PATCH and DELETE endpoint now accepts an optional Idempotency-Key header, so you can safely retry a request after a timeout without creating a duplicate, for example a second payout. A key can be used once per endpoint and is kept for at least 7 days. A retry with a key whose first request succeeded, or is still in progress, returns 409 Conflict with error code IDEMPOTENCY_KEY_NOT_UNIQUE and is not processed. If the first request failed, the key is released and you can retry with the same key. See Idempotency.

Change to POST /international_payouts: the Idempotency-Key header is optional, not required. Within the 7-day window, retrying with a used key now returns 409 IDEMPOTENCY_KEY_NOT_UNIQUE instead of 201 with the original payout. No duplicate payout is created in either case. To get the original payout, use GET /payouts.