# idempotency_key_required

> Every trade needs an Idempotency-Key.

Source: https://tickwire.io/docs/errors/idempotency_key_required/

HTTP 400. Nothing reached the broker.

**Likely cause:** The header is missing or too long.

**What to do:** Send a unique Idempotency-Key.

**Retry:** No. The same request gets the same answer; change something first.

Listed under [Orders and idempotency](https://tickwire.io/docs/errors/#orders-and-idempotency) in [Errors](https://tickwire.io/docs/errors/). Send the error's `requestId` to support and we can find the request.