# Invalid token

Resolve invalid token errors.

The `X-Token` header was provided but is malformed or has an invalid signature.

Verify how your backend generates [user identity tokens](/explanation/application/signed-tokens) before retrying.

## Response

All error responses follow the [Problem Details (RFC 9457)](/reference/api/overview#errors) format. The `type`, `title`, `status`, and `detail` fields are always present, while `instance` may be omitted depending on the API.

Here is an example of the response returned for this error:

```json
{
  "type": "https://croct.help/api/authentication/invalid-token",
  "title": "The token is invalid.",
  "status": 401,
  "detail": "The provided token is invalid or malformed.",
  "instance": "/client/web/content"
}
```