API errors

Concurrent request with the same idempotency key

A request with this Idempotency-Key is still in flight. To guarantee exactly-once semantics, the duplicate was rejected while the original is being processed.

Error type

https://normbill.com/docs/errors/idempotency-conflict

HTTP status

409

Common causes

• Two clients (or a retry loop) fired the same request in parallel.
• A retry was sent before the original request finished or timed out.

How to fix it

• Wait briefly and retry with the same key — once the original completes, the retry returns its result without double-charging.
• Avoid firing parallel duplicates; serialize retries with backoff.

The error response format

Every non-2xx response from the API is an RFC 9457 problem-details body (application/problem+json) with at least type, title, status and detail. The type URL links back to this reference.

All error slugs: invalid-request, bad-request, payload-too-large, unauthorized, validation-failed, unparseable-document, plan-limit, quota-exceeded, rate-limited, overage-cap-reached, validate-fair-use, idempotency-key-invalid, idempotency-key-reuse, idempotency-conflict, pdf-unavailable, validator-unavailable, not-ready. Still stuck? Email support@normbill.com or start at the docs overview.