Debug failed requests

When troubleshooting a request to https://gateway.ngrok.ai:

Record the Ngrok-AIG-Request-Id response header. Every response carries it, errors included, and it identifies the request in usage data.
Check the error code and message in the response body. See Error Codes.
Read Ngrok-AIG-Attempts to see whether failover ran. A count above 1 means the gateway tried more than one upstream candidate before it gave up, so the cause is upstream rather than in your request. An absent header means the request failed before any attempt, which points at the request body or the access key configuration.
Verify your app sends an access key—not an upstream provider key.
Confirm the access key’s configuration allows the provider and model you requested, with routing credentials attached.
Look the request up in the dashboard at app.ngrok.ai, or query it with the Usage API.

Common fixes:

Symptom	Check
401 Unauthorized	Access key missing, malformed, or deleted
403 Forbidden	Credits exhausted: purchase credits
No keys available for provider (27202)	Configuration missing a routing rule or provider keys for the requested provider
Provider or model not allowed by the access policy (27231, 27232)	Model or provider blocked by the configuration’s access scope
All retries exhausted (27208)	Every candidate failed. See Handle gateway errors
Response names a model you did not expect	Read `Ngrok-AIG-Model`, not the `model` field in the body. The body is passed through byte-for-byte and keeps the provider’s own wording

See Handle gateway errors for retry and failover behavior.