public function onRequestException(Event $event)
    {
        if (!$event['exception'] instanceof CurlException) {
            return;
        }

        $request = $event['request'];
        if (!$this->canCache->canCacheRequest($request)) {
            return;
        }

        if ($response = $this->storage->fetch($request)) {
            $response->setHeader('Age', time() - strtotime($response->getDate() ? : 'now'));
            if (!$this->canResponseSatisfyFailedRequest($request, $response)) {
                return;
            }
            $request->getParams()->set('cache.hit', 'error');
            $request->setResponse($response);
            $this->addResponseHeaders($request, $response);
            $event->stopPropagation();
        }
    }