internal_error
An uncaught failure on a route with no quiet-passthrough relay.
What it means
An uncaught failure on a route with no quiet-passthrough relay. /v1/chat/completions, /v1/execute, /anthropic/v1/messages, /v1/messages and the /azure/, /gemini/ and /bedrock/ surfaces never produce it: there, an internal fault relays the request to the provider instead (the fail-open guarantee below).
How to recognise it
The gateway answers HTTP 500 with x-ace-error: internal_error on the response. This refusal has no typed envelope of its own, so the header is the reliable signal; the body is the surface's usual error shape.
Is it ACE or the provider?
x-ace-error is present only on errors ACE originated. A vendor error relayed from upstream — a real provider 429, a provider 401 for a bad pass-through key — carries no x-ace-error, and its own type and code mean what the provider says. Read the header before deciding whether to retry, re-mint a key or surface the error.
Related
- Error contracts & status codes: the full taxonomy
- Response header specification
- Echo mode: reproduce a call without spending