> ## Documentation Index
> Fetch the complete documentation index at: https://apixo.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# LLM Errors & Retry: Safe Retry Strategy for the Gateway

> Troubleshoot APIXO LLM Gateway errors, understand which failures are safe to retry, and configure backoff for production traffic.

LLM Gateway calls are direct provider-compatible requests, not async generation tasks. Use the HTTP status code and response body to decide whether to fix the request or retry.

## Common errors

| Status | Common cause | What to do |
| - | - | - |
| `400` | Invalid request body, endpoint, model id, or provider-specific parameter | Fix the request before retrying |
| `401` | Missing or invalid APIXO API key | Check `APIXO_API_KEY` and the provider-compatible auth header |
| `403` | Account or key cannot access the requested resource | Check account access, balance, or model availability |
| `429` | Rate limit, quota limit, or temporary capacity limit | Retry with exponential backoff |
| `500` | Internal server error | Retry with backoff |
| `502` | Upstream provider error | Retry with backoff |
| `504` | Upstream timeout | Retry with backoff or reduce request size |

## Safe retry policy

Retry only transient failures such as `429`, `500`, `502`, and `504`.

```text theme={null}
1st retry: wait 1 second
2nd retry: wait 2 seconds
3rd retry: wait 4 seconds
then stop or hand off to a queue
```

Do not blindly retry:

* Authentication failures
* Invalid JSON or invalid request bodies
* Missing required provider headers
* Unsupported model names
* Requests that already produced a successful streamed response

## Debug checklist

1. Confirm the base URL matches the compatible API.
2. Confirm the API key is stored as `APIXO_API_KEY`.
3. Confirm the model name is supported by that API format.
4. Test the same request without streaming.
5. Save the response body and status code before contacting support.

<Tip>
  For generation task errors, use the general [Error Codes](/docs/api-reference/errors) page. This page is focused on direct LLM Gateway calls.
</Tip>


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