# 400 invalid_idempotency_key

**Invalid Idempotency-Key**

The Idempotency-Key header is missing or malformed.

- HTTP status: 400
- Problem identifier (`type` field): `https://developer.noryo.app/errors/invalid_idempotency_key`

[← Errors — Merchant API](https://developer.noryo.app/en-GB/errors)

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Canonical page: https://developer.noryo.app/en-GB/errors/invalid_idempotency_key