API error type
Too Many Requests
HTTP 429 https://errors.driftstack.dev/rate-limited
What it means
You exceeded the request rate limit for this endpoint class — or, on an AI agent-session message, your account already has as many AI turns running at once as it may, across your sessions or on Driftstack’s included AI. In that second case no step ran, and the limit clears by itself when a running turn finishes.
How to fix it
Wait the number of seconds in the retry_after_seconds extension (the Retry-After header carries the same value), then send the same request again — for an AI message that means the same Idempotency-Key too, because nothing ran. The SDKs retry most calls for you with backoff; an agent-session message and the transcript stream are yours to retry.
Where it appears
In the type field of the RFC 9457 application/problem+json error body, alongside title, status, detail, and an instance correlation id.
Related
- Concurrent session limit reached
/concurrency-limit - Tier limit reached
/tier-limit