HTTP 422Idempotency key reused with a different request body

idempotency_key_reused

This Idempotency-Key was already used within its 24-hour window with a DIFFERENT request body. Keys uniquely identify one logical request; reusing one for different content is always a client bug, so the API refuses rather than guessing.

This page is where the problem type URI https://usepostify.com/docs/api/problems/idempotency-key-reused resolves.

Common causes

  • A static or hardcoded key is reused across different posts.
  • The body is re-serialized differently between attempts (field order is fine; changed values are not).
  • A key-generation collision (e.g. truncated hash).

How to fix

  • Generate one fresh key (a UUID) per logical create, and reuse it only for byte-equivalent retries of that same create.
  • Persist the key alongside your outbound job so retries reuse it deliberately.

Example response

422 · application/problem+json
{
  "type": "https://usepostify.com/docs/api/problems/idempotency-key-reused",
  "title": "Idempotency key reused with a different request body",
  "status": 422,
  "code": "idempotency_key_reused",
  "detail": "This Idempotency-Key was already used with a different request body.",
  "request_id": "req_6f1f8a2b40d34cd2a6f1e2c9b8d7a601"
}

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