# Errors

If for any reason the **PKSA** fails to process the challenge request, it can send an error message to the **HAS** that will forward it to the **APP**. The same applies if the error is generated by the **HAS**.

In both cases, the **APP** will receive the following message:

### challenge\_err

```
{
    cmd: "challenge_err",
    uuid: string,
    error: string
}
```

{% tabs %}
{% tab title="Properties" %}
* **`uuid`**: the transaction request identifier
* **`error`**: an error message encrypted with the `auth_key`
{% endtab %}
{% endtabs %}
