# Unauthorized

**HTTP Status:** 401 Unauthorized
**RFC Reference:** [RFC 9110 Section 15.5.2](https://datatracker.ietf.org/doc/html/rfc9110#section-15.5.2)

The request requires authentication. Please provide valid credentials.

## Common Causes

- Missing `Authorization` header
- Invalid access token
- Expired access token
- Malformed bearer token


## How to Fix

1. Ensure you include the `Authorization` header
2. Request a new access token if expired
3. Verify token format: `Bearer YOUR_TOKEN`


See [Authentication guide](/getting-started/authentication) for details.