What causes " " in apify/crawlee?

Verify proxy credentials (username/password) and proxy URL in your ProxyConfiguration are current.

apify/crawlee · warning · SessionError

<dynamic: message extracted from proxied error via getMessag

Error message

<dynamic: message extracted from proxied error via getMessageFromError>

What it means

Inside the crawler's requestFunction, errors are inspected after the request fails; if `isProxyError()` classifies the thrown error as a proxy-level failure (e.g. proxy connection refused, 407, tunnel errors), it is re-thrown as a SessionError carrying the original message extracted via getMessageFromError. This marks the session as bad so the request is retried through a different proxy instead of failing the whole request.

Source

Thrown at packages/http-crawler/src/internals/http-crawler.ts:708

    /**
     * Function to make the HTTP request. It performs optimizations
     * on the request such as only downloading the request body if the
     * received content type matches text/html, application/xml, application/xhtml+xml.
     */
    private async requestFunction({ request, session, proxyUrl }: RequestFunctionOptions): Promise<Response> {
        const opts = this.getRequestOptions(request, session, proxyUrl);

        try {
            return await this.requestAsBrowser(opts, session);
        } catch (e) {
            if (e instanceof Error && e.constructor.name === 'TimeoutError') {
                this.handleRequestTimeout(session);
                return new Response(); // this will never happen, as handleRequestTimeout always throws
            }

            if (this.isProxyError(e as Error)) {
                throw new SessionError(this.getMessageFromError(e as Error) as string);
            } else {
                throw e;
            }
        }
    }

    /**
     * Encodes and parses response according to the provided content type
     */
    private async parseResponse(request: CrawleeRequest, response: Response) {
        const { status } = response;
        const { type, charset } = parseContentTypeFromResponse(response);
        const { response: reencodedResponse, encoding } = this.encodeResponse(request, response, charset);
        const contentType = { type, encoding };

        if (status >= 400 && status <= 599) {
            this.statistics.registerStatusCode(status);
        }

View on GitHub (pinned to dbe57fb09c)

Solutions

Verify proxy credentials (username/password) and proxy URL in your ProxyConfiguration are current.
Test the proxy directly (curl -x proxy_url target_url) to confirm it works outside crawlee.
Ensure session pool is enabled so bad sessions are retired and the request retries on a healthy proxy.
Check your proxy provider's dashboard for quota exhaustion or IP pool health; switch pools if needed.

Example fix

// before
proxyConfiguration: await Actor.createProxyConfiguration({ groups: ['RESIDENTIAL'] }),

// after: validate proxy before crawling
const proxyConfiguration = await Actor.createProxyConfiguration({ groups: ['RESIDENTIAL'] });
const proxyUrl = await proxyConfiguration.newUrl();
const res = await got('https://api.apify.com/v2/public-proxy-ip', { proxyUrl, throwHttpErrors: false });
if (res.statusCode >= 400) throw new Error(`Proxy unhealthy: ${proxyUrl}`);

Defensive patterns

Strategy: try-catch

Validate before calling

const proxyUrl = await proxyConfiguration.newUrl();
const probe = await got('https://httpbin.org/ip', { proxyUrl, throwHttpErrors: false, timeout: 10000 });
if (probe.statusCode !== 200) throw new Error(`Proxy probe failed: ${probe.statusCode}`);

Type guard

function isProxySessionError(err: unknown): err is SessionError {
  return err instanceof SessionError && /proxy/i.test(err.message);
}

Try / catch

try {
  await crawler.run(requests);
} catch (err) {
  if (err instanceof SessionError && /proxy|tunnel|407/i.test(err.message)) {
    log.error(`Proxy infrastructure problem, aborting: ${err.message}`);
    return;
  }
  throw err;
}

Prevention

Validate proxy credentials and quota before starting large crawls.
Smoke-test one request through the proxy pipeline before full runs.
Prefer provider proxy groups with health monitoring; rotate groups on repeated proxy errors.
Log proxy session IDs on failure to correlate with provider logs.

When it happens

Trigger: The underlying HTTP request (got) rejects with a proxy-related error while a proxyConfiguration is in use — e.g. proxy authentication failed, proxy unreachable, or the proxy returned an error response.

Common situations: Expired or wrong proxy credentials; datacenter IPs blocked by the target; proxy provider outage; residential proxy session exhausted; running locally without the proxy reachable from the network.

Related errors

AI-assisted analysis of apify/crawlee@dbe57fb09c (2026-08-30). Data as JSON: /api/errors/3719bca36b0bcde5. Report an issue: GitHub.