Idempotency key missing

Identifiers

Field	Value
Type URI	https://echo.labstack.com/pro/problems/idempotency-key-missing
Code	idempotency_key_missing
HTTP status	400

HTTP status	English title
400	Bad Request

When it occurs

The request has no idempotency key. The header is Idempotency-Key unless the operation configures another name. Nothing was recorded, and the handler did not run.

Client handling

Send one key for each logical operation, and reuse the same key and request when you retry that operation.

Example response

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

HTTP/1.1 400 Bad Request
Content-Type: application/problem+json
Cache-Control: no-store

{
  "code": "idempotency_key_missing",
  "operation_ref": "",
  "operation_state": "",
  "safe_new_key": false,
  "status": 400,
  "title": "Bad Request",
  "type": "https://echo.labstack.com/pro/problems/idempotency-key-missing"
}

Server correction

Have the client generate one key before the first attempt and retain it across retries. Generating a new key on each retry can run the operation twice.

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.