openrtb.schain.length_implausible
What it means
The SupplyChain object declares more than ten nodes. Real paths run to a handful of hops: a publisher's SSP, perhaps a reseller, perhaps an exchange in front of the bidder.
Why it matters
Every hop has to be independently authorised in that system's sellers.json for the chain to verify, so a very long path is both expensive to audit and unlikely to be genuine. In practice it is usually a concatenation bug where a forwarder appends the upstream chain twice, and occasionally it is a laundered path.
How to fix it
Log the chain at each hop and find the point where the node count jumps. Appending should add exactly one node per system, never splice two chains together.
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.
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