# Not Found
URL: /reference/problems/not-found

The API returns a `404 Not Found` status with this problem type when the requested resource cannot be found.

## Response Format

```json
{
  "type": "https://docs.tambo.co/reference/problems/not-found",
  "status": 404,
  "title": "Not Found",
  "detail": "Thread not found",
  "instance": "/threads/thread_123"
}
```

## Fields

* **`type`** - Stable URI identifying this problem type
* **`status`** - HTTP status code (always `404`)
* **`title`** - Short summary of the problem (always `Not Found`)
* **`detail`** - Human-readable description of what could not be found
* **`instance`** - The specific request path that triggered this error

## Handling

When you receive this error:

1. Verify the resource ID in your request
2. Confirm the resource exists (and that your project has access to it)
3. Retry with a valid ID

## See Also

* [REST API Reference](/reference/rest-api) - Complete API documentation
* [RFC 9457 Problem Details](https://www.rfc-editor.org/rfc/rfc9457.html) - Standard for error responses