RTBlintAlpha
nbr 2: Invalid Request
What it means
The bid request itself was malformed or failed the bidder's validation.
A bidder returns nbr on an otherwise empty BidResponse to say why it is not bidding, instead of (or alongside) an HTTP 204. Code 2 is invalid request.
What to do about it
These codes mean the bidder could not process the request at all. If you are the seller receiving them, first validate the requests you send: a request that fails a bidder's parser produces exactly this family. If you are the bidder emitting them, your own logs, not the exchange's, hold the cause.