Idempotency key reused

Identifiers

Field	Value
Type URI	https://echo.labstack.com/pro/problems/idempotency-key-reused
Code	idempotency_key_reused
HTTP status	422

HTTP status	English title
422	Unprocessable Entity

When it occurs

The key already belongs to another request. This request’s fingerprint differs from the first recorded request.

Client handling

Do not change a request while you retry it under the same key. To get the original operation’s answer, resend the original request with that key. Use a new key only for a new, different operation.

Example response

If your application installs a custom handler, the body may differ.

HTTP/1.1 422 Unprocessable Entity
Content-Type: application/problem+json
Cache-Control: no-store

{
  "code": "idempotency_key_reused",
  "operation_ref": "",
  "operation_state": "",
  "safe_new_key": false,
  "status": 422,
  "title": "Unprocessable Entity",
  "type": "https://echo.labstack.com/pro/problems/idempotency-key-reused"
}

Server correction

Check which request fields FingerprintSpec includes. Keep fields that change business behavior in the fingerprint.

Response fields

Execution middleware

• type (string, always): The exact type URI above.
• title (string, always): The HTTP status text.
• status (integer, always): The HTTP status of the response.
• code (string, always): The stable code above.
• operation_ref (string, always): An opaque reference to the operation. It is set only after ReplayCheck allows the request, and is empty when no operation was found. Use it to look up the operation; it does not grant access.
• operation_state (string, always): started, uncertain, completed or failed; empty when no operation was found.
• safe_new_key (boolean, always): true only when the client may retry with a new key. It is always false when operation_ref and operation_state are empty.

Headers:

• Cache-Control (always): no-store on every execution problem.

Notes:

• Execution removes any Idempotent-Replayed header from problem responses.

Related behavior

See execution for operation state and replay rules.