# Operation Error

```javascript
class OperationError extends Error {
      code: string;
      message: string;
      data: string;
}
```

**data** has a value if return data for an incomplete session is enabled and the user successfully passed the first scan step.

<table><thead><tr><th width="326">Error Code</th><th>Description</th></tr></thead><tbody><tr><td>UNEXPECTED_ERROR</td><td>Generic network error</td></tr><tr><td>UNAUTHORIZED</td><td>Token expired or invalid</td></tr><tr><td>FORBIDDEN</td><td>The requested feature is not enabled for your token</td></tr><tr><td>SESSION_EXPIRED_OR_NOT_FOUND</td><td>Session expired or not found</td></tr><tr><td>MEDIA_NOT_ALLOWED_ERROR</td><td>Camera not allowed by the user</td></tr><tr><td>MEDIA_NOT_FOUND_ERROR</td><td>Camera not found</td></tr><tr><td>MEDIA_SECURITY_ERROR</td><td>The device not allowed access to camera</td></tr><tr><td>MEDIA_UNKNOWN_ERROR</td><td>This device/platform/browser/version combination is not supported<br><strong>Note</strong>: In order for the SDK to access the camera your website needs to use https, see <a href="https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia">https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia</a></td></tr><tr><td>MEDIA_VIRTUAL_CAMERA_DETECTED</td><td>Virtual camera usage has been detected</td></tr><tr><td>USER_CANCEL</td><td>The user drop the session</td></tr><tr><td>INVALID_CONFIG</td><td>Invalid configuration</td></tr><tr><td>SESSION_INVALIDATED_FACE_RECOGNITION_TOO_MANY_ATTEMPTS</td><td>Too many failed facial recognition attempts</td></tr><tr><td>WASM_NOT_SUPPORTED</td><td>The browser lacks the essential features required to run a WASM module</td></tr></tbody></table>