# Forbidden
URL: /reference/problems/forbidden

The API returns a `403 Forbidden` status with this problem type when the request is understood, but not allowed.

## Response Format

```json
{
  "type": "https://docs.tambo.co/reference/problems/forbidden",
  "status": 403,
  "title": "Forbidden",
  "detail": "Project does not allow overriding the system prompt with initial messages",
  "instance": "/threads"
}
```

## Fields

* **`type`** - Stable URI identifying this problem type
* **`status`** - HTTP status code (always `403`)
* **`title`** - Short summary of the problem (always `Forbidden`)
* **`detail`** - Human-readable description explaining why the request was rejected
* **`instance`** - The specific request path that triggered this error

## Handling

When you receive this error:

1. Confirm your project configuration allows the operation you're attempting
2. Update the request to comply with the current configuration (or change the configuration)
3. Retry the request

## 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