$response = $fb->get('conv-id','auth-token');

<?php
    require_once ('C:/Users/koran/vendor/autoload.php'); // change path as needed
    /* PHP SDK v5.0.0 */
    /* make the API call */
    try {
      // Returns a `FacebookFacebookResponse` object
      $response = $fb->get( //<-- Error
        '/converstationid',
        'auth'
      );
    } catch(FacebookExceptionsFacebookResponseException $e) {
      echo 'Graph returned an error: ' . $e->getMessage();
      exit;
    } catch(FacebookExceptionsFacebookSDKException $e) {
      echo 'Facebook SDK returned an error: ' . $e->getMessage();
      exit;
    }
    $graphNode = $response->getGraphNode();
    /* handle the result */
?>