# X_FLIGHT_GATE_OVERLOADED

## Means

a concurrency gate is at its ceiling and its queue is full

## Typical cause

more callers asked for a bounded resource than `flightGate({ maxConcurrent, maxQueued })` admits — argon2 hashes, a browser pool, any work whose cost is memory rather than CPU time. Past the queue bound the answer is a refusal and never a longer queue: an unbounded queue turns a load spike into a memory fault and answers it minutes late. `meta` carries `active`, `queued`, both bounds and `retryAfterSeconds`, so it is classified `retry-after` and `@ultimat3/http` renders the header from it

## Fix

retry after the `Retry-After` header, or widen the ceiling at the `flightGate({ maxConcurrent, maxQueued })` call site — only if the box has the capacity the extra slots buy

[Core and runtime](/error-codes#core-and-runtime)