public function notifyObservers() {
    /**
     * restore original error handler, to avoid problems when errors occurres
     * in handling other errors
     */
    $this->Web2All->restoreErrorHandlers();
    foreach($this->observers as $observer) {
      $observer->update($this);
    }
    foreach($this->observer_names as $classname) {
      $this->Web2All->PluginGlobal->$classname->update($this);
    }
    // set custom error handlers back
    $this->Web2All->setErrorHandlers();
  }