---
title: 1014: Idempotency key invalid. | API Docs
description: Idempotency-Key is missing, repeated or malformed.
---

**HTTP status:** `400` or `422`, depending on the request.

The Idempotency-Key header must be supplied exactly once as 1-255 visible ASCII bytes on every operation that requires it. A missing or malformed header is refused before the operation runs (400); one refused by the operation itself answers 422. The request was not accepted.

## Troubleshooting

- Send one Idempotency-Key header per request, generated per logical operation, and reuse it only to replay that same request.

## Related

- [Sending a message](/channel/whatsapp/api/resources/chats/subresources/messages/methods/send/index.md)