# Error responses > Parse the common Router error envelope and recover according to status and code. Router returns errors as JSON before a stream starts. ```json { "error": { "message": "No provider is available for this model", "type": "server_error", "code": "no_priced_provider_available" } } ``` Use the HTTP status for broad control flow, the stable `code` for a specific product message, and `message` for a human-readable explanation. ## Common API errors | Status | Code or category | Recovery | | ------ | ------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | 400 | Invalid body, unknown model, `output_limit`, `prompt_too_large`, or unsupported input | Correct the request before trying again. | | 400 | `context_length_exceeded` | The messages exceed the edition’s context window in tokens. Shorten them before trying again. | | 400 | `stream_required` | A non-streaming request asked for more than 512 output tokens or sent more than about 24 KB of message text. Set `stream` to `true`, or shorten the request. | | 400 | `idempotency_key_required` | Send a caller-generated UUID in `Idempotency-Key`. | | 401 | `auth_no_token` or `invalid_api_key` | Supply a valid bearer key or rotate an expired or revoked key. | | 402 | `insufficient_credits` | Add shared credits or lower the request maximum. | | 402 | `budget_exhausted` | Router's UTC monthly spending cap is reached. | | 402 | `charge_limit_exceeded` | This request's worst-case charge exceeds its authorized maximum. | | 403 | `account_disabled` | Resolve account access; repeated requests will not help. | | 409 | `provider_price_changed` | Review the current selected offer price and explicitly accept its new revision in a new logical request. | | 409 | `provider_offer_unavailable` | Select another published eligible offer, or explicitly omit the selection for Auto. | | 409 | `idempotency_conflict` | This UUID was already used with a different body, credential, or `X-Max-Charge-Credits` value. Resend the original terms, or use a new UUID for a new request. | | 409 | `request_in_progress` | Router is still admitting the earlier request with this UUID. Check its credit receipt, then retry with the same UUID and body if needed. | | 409 | `request_already_exists` | A streaming request with this UUID already exists. Streams are not replayed; check its credit receipt. | | 429 | Request-rate or concurrency limit | Respect `Retry-After` and reduce parallel work. | | 503 | `no_priced_provider_available` | No eligible paid provider can accept this model now. | | 503 | `no_provider_for_length` | No online provider serves a request this long right now. Shorten the messages or the answer limit; an immediate retry will not help, so respect `Retry-After` (60 seconds). | | 503 | `selected_provider_unavailable` | The selected computer is busy or offline; Router does not silently fall back. | | 503 | `self_provider_only` | Select a provider owned by another account. | | 503 | `request_capacity` | Router’s bounded active-request capacity is full; retry later. | | 503 | `credit_admission_unavailable` or `settlement_pending` | Keep the request UUID and check its credit receipt; never start a new paid request just to recover. | | 503 | `slippage_tolerance_exceeded` | No charge or reservation. Review `error.minimum_slippage_tolerance` and submit new terms with a new request UUID if appropriate. | | 503 | `pricing_pending` | Pricing research is running; no charge or reservation. Retry unchanged terms after `Retry-After`. | | 503 | `suggested_price_unavailable` | Baseline storage or generation is unavailable; no charge or reservation. Retry later or choose another model. | | 503 | Generation or dependency failure | Show a temporary failure and retry the same logical request ID only when safe. | Error messages can evolve. Branch application behavior on status and code rather than matching the English message. ## Streaming errors After streaming headers are sent, a generation failure arrives as an SSE data event with an `error` object and the request's `request_id`. The HTTP status may already be 200. ```text data: {"error":{"message":"Generation or settlement interrupted","type":"server_error","code":"provider_timeout"},"request_id":"$REQUEST_ID"} data: [DONE] ``` An error event is terminal for that generation. A `[DONE]` marker may still follow; it does not turn the reply into a success. Do not treat already-received content as a complete answer, and check the request's credit receipt before retrying. Codes vary by failure. When streaming, an input longer than the model's context window arrives this way too, as `"type":"invalid_request_error","code":"context_length_exceeded"` with no answer text. Retrying the same messages fails again: shorten them first. No tokens were generated, so the request's reservation is released. ## Retry headers 429 and temporary capacity responses can include `Retry-After`. Interpret an integer value as seconds, add jitter before retrying, and keep the total number of attempts bounded. > **Keep one ID for one request** > Retry an uncertain result with the same `Idempotency-Key` UUID and unchanged body. A new UUID starts a separate paid request and can create another charge. See [retries, timeouts, and cancellation](https://router.optimai.network/docs/retries-and-timeouts.md) for an application strategy.