idempotency_in_flight

A request with this Idempotency-Key is still running. This request was not sent (`sent: false`); the earlier one may still execute.

HTTP 409. Unknown: it may have executed. Resolve it with the same idempotency key before acting.

Likely cause: A retry arrived before the first attempt finished, for example after a gateway timeout (504) or a client-side timeout.

What to do: Wait Retry-After seconds, then repeat with the same key: once the first attempt finishes you get its stored result. Never switch to a new key while the outcome is open, and check positions and orders (or the trade status by key) first.

Retry: Only with the same Idempotency-Key (or clientId). The first attempt may have executed; never resend a trade blindly.

Listed under Orders and idempotency in Errors. Send the error’s requestId to support and we can find the request.