Why is my bidder not receiving bid requests?

Answer

Work the path from the exchange inward: confirm the endpoint the exchange has on file matches what you deployed (scheme, host, path), that your endpoint returns a well-formed response or HTTP 204 quickly enough to stay under the exchange's timeout, and that traffic filters on the exchange side (geo, media type, QPS caps, pretargeting) are not excluding you. Exchanges routinely throttle or suspend bidders whose error or timeout rate climbs, so a bidder that once received traffic and stopped usually failed health checks. Ask the exchange for its bidder health report; most expose error and timeout rates per endpoint.

More questions on debugging, no-bids, and validation

All 93 questions are listed in the OpenRTB FAQ.