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

# API errors

> Common error response formats and codes returned by Circle APIs.

Circle APIs return an
[HTTP status code](https://en.wikipedia.org/wiki/List_of_HTTP_status_codes) when
they encounter an error:

* `4xx` errors are client errors. They communicate a mistake in the request and,
  where possible, suggest a fix.
* `5xx` errors are unexpected server-side errors.

Product-specific error codes are documented on each product's error codes page.
See [Wallets](/api-reference/wallets/error-codes),
[Contracts](/api-reference/contracts/error-codes),
[Mint](/api-reference/circle-mint/error-codes), and
[CPN](/api-reference/cpn/error-codes).

## General error format

HTTP status codes do not always provide sufficient information to determine the
cause of the error. The response body contains additional Circle-specific error
information. For example, if a request contains an invalid parameter, the
response includes the following:

**Header**

```http theme={null}
HTTP/1.1 400 Bad Request
Content-Type: application/json
```

**Body**

```json theme={null}
{
  "code": 2,
  "message": "API parameter invalid"
}
```

## Extended error format

For validation failures, the response includes an `errors` array with per-field
detail. For example, if a request is missing a required field:

**Header**

```http theme={null}
HTTP/1.1 400 Bad Request
Content-Type: application/json
```

**Body**

```json theme={null}
{
  "code": 2,
  "message": "API parameter invalid",
  "errors": [
    {
      "error": "required",
      "message": "fail to bind request to CreateWalletSetRequest: EOF",
      "location": "field1",
      "invalidValue": "null",
      "constraints": {}
    }
  ]
}
```

## General errors

The following errors can be returned for any request.

| Error code | HTTP code | Error message           | Resolution                                                                                |
| ---------- | --------- | ----------------------- | ----------------------------------------------------------------------------------------- |
| `-1`       | `400`     | `Something went wrong`  | An unknown error occurred. Retry with exponential backoff.                                |
| `3`        | `403`     | `Forbidden`             | The API key does not have access to the requested endpoint.                               |
| `2`        | `400`     | `API parameter invalid` | The request body or a parameter value is invalid. Read the `message` field for specifics. |