Rejected Diameter request because the adjacency in-flight request limit was reached

Logged when a peer sends an application request while its adjacency already has as many requests in policy processing as the fixed per-adjacency bound, logged as maximum_in_flight_requests, allows. Requests received on an earlier connection of the same adjacency count until their processing ends, even after that connection closed. Radiator answers with diameter_result_code: 3004 (DIAMETER_TOO_BUSY) when the request's Destination-Host names this local node and 3002 (DIAMETER_UNABLE_TO_DELIVER) otherwise, so the peer can retry through another agent. The connection keeps reading, so answers and watchdog traffic continue.

Compare the request rate of the logged peer with the time policy processing takes. Slow backends or forwarding destinations keep requests in processing longer; fix their latency or spread the load over more peers. A peer that reconnects repeatedly while its requests are still in processing also reaches the bound.