Errors
Errors use the same envelope as successful calls: success is false, data is null, and error carries a human-readable message. Check success rather than parsing the message — wording can change.
Status codes
400Validation failed — a required field is missing or malformed. Fix the payload; retrying as-is will fail again.
401The API key is missing, unknown or revoked.
404The car, booking or driver does not exist under your owner account.
409The resource is already taken — e.g. the transponder or GPS device belongs to another vehicle or owner.
500Unexpected server error. Safe to retry with backoff; contact support if it persists.
Retries and idempotency
Reads are safe to retry. For writes, retry only on network failures and 5xx, and use your own ids (externalId) so a repeated create resolves to the same record instead of a duplicate.