> For the complete documentation index, see [llms.txt](https://docs.fastnode.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fastnode.io/reference/error-codes.md).

# Error Codes

FastNode returns standard HTTP status codes for transport-level issues and JSON-RPC error objects for method-level issues.

## HTTP status codes

| Code  | Meaning             | How to fix                                          |
| ----- | ------------------- | --------------------------------------------------- |
| `200` | Success             | —                                                   |
| `400` | Malformed request   | Check your JSON body and method name.               |
| `401` | Unauthorized        | Missing or invalid API key.                         |
| `403` | Forbidden           | Key doesn't have access to this network/method.     |
| `429` | Too Many Requests   | You hit a rate limit — see below.                   |
| `500` | Internal error      | Retry with backoff; contact support if it persists. |
| `503` | Service unavailable | Node temporarily unavailable; retry with backoff.   |

## JSON-RPC errors

Method-level errors come back in the response body:

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "error": { "code": -32602, "message": "invalid argument" }
}
```

| Code     | Meaning          |
| -------- | ---------------- |
| `-32700` | Parse error      |
| `-32600` | Invalid request  |
| `-32601` | Method not found |
| `-32602` | Invalid params   |
| `-32603` | Internal error   |

## Rate limits

A `429` means you've exceeded your plan's per-second or monthly quota. Implement exponential backoff and, if you consistently hit limits, upgrade your plan or request a dedicated node at **<support@fastnode.io>**.

{% hint style="info" %}
Retry `429`, `500`, and `503` with exponential backoff and jitter. Do **not** blindly retry `400`/`401`/`403` — fix the request or credentials first.
{% endhint %}


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