openrtb.request.cur_format_invalid

What it means

An entry in the request's cur array, the list of currencies bids may use, is not shaped like an ISO 4217 code: three uppercase letters (USD, EUR, JPY). Lowercase, symbols, or full currency names land here.

Why it matters

Buyers match bid currency against this list literally. An entry like "usd" or "$" matches nothing, so bidders either fall back to assuming USD or skip the request, and cross-currency demand you meant to invite never arrives.

How to fix it

Use uppercase ISO 4217 alpha-3 codes, one per allowed currency. If you only transact in USD you can omit cur entirely, since USD is the default assumption.

Example that trips it

{ "cur": ["usd", "€"] }

Check your payload

Paste a bid request or response into the tester to see whether this code fires against it, or gate on the id in CI with the CLI: the id is stable, wording is not.

Back to the full diagnostic code reference.