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

# Upstream Errors

Upstream errors come from the model provider or its gateway. They usually mean the request was already forwarded upstream and the upstream returned an error response.

## Common causes

* Request parameters do not meet protocol requirements (missing fields, wrong types, invalid values)
* Authentication failure (upstream Key/permission issues)
* Upstream rate limiting or overload
* Upstream service failure or maintenance

## How to identify

Check the source identifier in the response headers:

```text theme={"theme":{"light":"min-light","dark":"min-dark"}}
Poixe-Error-Source: upstream
Poixe-Request-Id: <request_id>
```

In addition, the response body of an upstream error generally preserves the original error structure of the upstream protocol (which may vary by protocol).

## Recommendations

* For parameter errors: first check the request body fields against the documentation page of the corresponding protocol
* For rate limiting/overload: implement backoff and retry on the client (and reduce concurrency)
* For occasional 5xx errors: you can retry; if they persist, contact the team with the Request ID


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