What does the VARTA error `idempotency_key_reuse` mean?

HTTP status: 409  ·  Type: invalid_request_error

What it means

The Idempotency-Key you sent was already used, with a different request body.

What causes it

The idempotency layer fingerprints method, path and body per key; a stored fingerprint that doesn't match the current request raises this (backend/app/api/v1/idempotency.py).

What to do

Generate a new key per logically distinct request. Never reuse one key across two different request bodies.