Retry-After when the response has one. Errors never cost API credits.
Asking for items Alura has never seen starts a fetch from Etsy, and fetches have their own daily caps per type and a per-minute rate. Known items are not affected. Retry-After says when the next fetch can start; GET /v1/usage shows the day’s fetch_caps.
What to do: Wait for Retry-After before asking for items Alura has not seen.
Response
application/problem+json (RFC 9457) and has a Request-Id header with the same request_id. See all errors.