RTBResponse id does not echo the RTBRequest id
The response id is not the extension point request id. The envelope id is not the bid request id, and confusing the two is the common failure.
What it means
RTBResponse.id carries something other than the RTBRequest.id it answers. The usual value found here is the bid request id, which sits one level deeper, inside bid_request.
Why it matters
The two ids are adjacent, similar looking, and assigned by different parties: the envelope id is the exchange's handle for this extension point call, while the bid request id identifies the auction. An agent that echoes the wrong one produces mutations the orchestrator drops as unmatched, and the symptom is an agent that appears to return nothing.
How to fix it
Echo the top-level RTBRequest.id, not bid_request.id.
Example that trips it
{ "id": "auction-9001", "mutations": [], "metadata": { "api_version": "1.0.0" } }The auction id echoed where the extension point request id belongs.
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.