> For the complete documentation index, see [llms.txt](https://docs.sparkloop.app/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sparkloop.app/client-api/errors-and-warnings.md).

# Errors & Warnings

### Error handling

When a call fails, its promise rejects with a `ClientApiError` carrying three properties:

* `error` — machine-readable error code.
* `message` — human-readable explanation.
* `status` — the HTTP status of the failed request.

```js
try {
  await SL.client.recommendations.subscribe({ email, uuids });
} catch (error) {
  if (error.name === "ClientApiError") {
    console.error(error.error, error.message);
  }
}
```

The errors you're most likely to run into:

* `bad_request` (400) — a required argument is missing or invalid: a missing or malformed `email`, or a missing `uuid` or `uuids`.
* `not_found` (404) — the `uuid` you passed doesn't match any of your recommendations or offers.
* `forbidden` (403) — the Client API is not enabled for your publication, or the page's origin is not registered as an allowed origin. See [Early Access](/client-api/early-access.md) to get it enabled or add a domain.

If the SparkLoop script itself fails to initialize, `SL.client` methods reject with a regular `Error` instead of a `ClientApiError`.

### Subscribe and claim only with consent

{% hint style="danger" %}
Readers must explicitly choose the recommendations you subscribe them to and the offers you claim for them, without being misled in any way. Failure to comply results in a permanent block of your SparkLoop account.
{% endhint %}

### Never cache recommendations or offers

{% hint style="warning" %}
Recommendations and offers are generated for a specific reader at a specific moment, and their availability changes continuously. If a recommendation or offer is no longer recommendable by the time your `subscribe` or `claim` call arrives, it is discarded: the call still succeeds, but nothing is registered and nothing is earned.
{% endhint %}

To stay safe:

* Never cache or store recommendations or offers — not even for a few hours.
* `generate` right before displaying, and `subscribe`/`claim` right after the reader acts.
* When spotlighting an individual recommendation or offer, `fetch` it right before displaying it and check its `recommendable` field.