A fast way to stop 502s is to slow your scraper, retry with backoff and jitter, rotate a clean proxy or IP, and send real browser headers. This is the core of how to fix 502 error during web scraping. Also check if the site itself is down. Most 502s fade once you reduce load and look like a real user.

Quick answer: how to fix 502 error during web scraping

Confirm the site is up by visiting it in a browser or using a status checker.

Retry failed requests with exponential backoff and random jitter.

Lower concurrency and add a crawl delay (e.g., 1–3 seconds).

Rotate proxies; drop bad IPs; test without a proxy if possible.

Send realistic headers: User-Agent, Accept, Accept-Language, Accept-Encoding.

Keep sessions clean: reset cookies, handle redirects, and respect robots.txt.

Switch to HTTP/1.1 if HTTP/2 shows issues; enable keep-alive; tune timeouts.

Block heavy assets (images, video, ads) in headless browsers to reduce strain.

What a 502 Bad Gateway means

A 502 Bad Gateway means a server that sits in front of the real app server got a bad response from it. That server might be a load balancer, a CDN, a reverse proxy, or a web firewall. Your request reached the edge, but the edge could not get a clean answer from the origin. During scraping, this often happens when:

The origin is busy or rate-limited and drops connections.

The proxy or CDN sees many similar requests and flags them as risky.

Your proxy IP is low quality or already blocked.

Your request is malformed or missing key headers.

Network timeouts or DNS hiccups break the chain between edge and origin.

502 is not the same as 403 (forbidden), 429 (too many requests), 503 (service unavailable), or 504 (gateway timeout). But the fix steps overlap: slow down, retry smartly, and look like a normal browser.

Fast first aid: Get back to green

1) Check the target

Open the page in a browser. If the site shows a 502 or loads slow, the issue is on their side. Pause your crawl and try again later. If the site is fine, continue with the steps below.

2) Retry with backoff and jitter

Do not hammer the same URL. Use exponential backoff (for example, 1s, 2s, 4s, 8s) plus a small random delay. Limit retries to 3–5 attempts. Backoff prevents spikes and reduces stress on the server.

3) Reduce parallel requests

If you send 50 threads, drop to 5–10. Add a small delay between hits to the same host. Concurrency is the number one cause of intermittent 502s during scraping.

4) Rotate or remove proxies

Some 502s are caused by weak or overloaded proxies. Test the same URL without a proxy if you can. Swap to a fresh residential or ISP proxy pool. Remove any IP that fails more than two times in a row.

5) Fix headers to look human

Send a modern desktop or mobile User-Agent. Add Accept, Accept-Language, and Accept-Encoding: gzip, deflate, br. Realistic headers often bypass fragile edge checks and trigger better routing.

Stabilize your scraper for the long run

Timeouts and connection reuse

Set a connect timeout (e.g., 5–10 seconds) and a read timeout (e.g., 20–30 seconds).

Use HTTP keep-alive so you reuse sockets. Fewer handshakes mean fewer corner-case errors.

If HTTP/2 is flaky, force HTTP/1.1. If HTTP/2 works, it can also improve stability.

Smart scheduling

Crawl during off-peak hours for the target timezone.

Spread traffic across time with a queue and a token bucket rate limiter.

Group URLs by host and cap per-host concurrency.

Session hygiene

Clear cookies if you see repeated 502s on the same path.

Follow redirects (3xx) and carry forward cookies and headers.

Avoid sending broken or stale auth tokens. Re-login or refresh tokens on failure.

Tuning requests that get blocked less

Craft polite, consistent requests

Servers trust stable patterns. Keep your header order, accept common encodings, and avoid weird Accept headers that browsers never send. When scripting headless browsers, let the browser set defaults, then add only what you need.

Control payload size

Do not send huge query strings or many useless query params.

Avoid downloading heavy assets. Block images, video, and fonts in headless mode.

Paginate and cache where possible to cut repeat hits.

DNS and TLS checks

Resolve the domain once and reuse the IP for a short time, but refresh regularly.

Ensure your system time is correct; wrong time can break TLS handshakes and cause upstream errors.

If you use custom SNI or HTTP/2, test a plain setup first. Simple often wins.

Work with the target, not against it

Respect robots.txt and TOS

Check robots.txt. If disallowed, do not scrape. If allowed, honor crawl-delay and be gentle. Ethical scraping lowers the chance of being blocked.

Use official channels if available

If the site has an API, use it. Many 502 headaches disappear when you switch from HTML scraping to the supported interface. APIs often have fair rate limits and stable responses.

Cache and deduplicate

Cache responses short-term so you do not request the same page twice.

Deduplicate URLs to avoid accidental loops.

Use sitemaps or feeds when available; fewer random hits mean fewer errors.

Debugging like a pro

Log the right details

When a 502 hits, log:

URL, method, and status code.

Timing (DNS, connect, TLS, first byte, total).

Proxy IP used and attempt number.

Response headers from the edge (e.g., via, cf-ray, server).

These clues tell you where the chain broke: your side, the edge, or the origin.

Compare browser vs script

Load the page in a normal browser and inspect the Network tab. Copy the request headers from a successful browser request. Align your script’s headers and cookies to match that pattern.

Try a HEAD or small GET first

Before fetching a heavy page, ping with HEAD or a small GET to warm the connection and verify availability. If that works, fetch the full page.

Language-specific tips

Python (requests, httpx)

Use a Session to reuse connections.

Set timeouts on every request, not just globally.

Mount a retry strategy with backoff for 5xx codes (except when the site forbids retries).

Add realistic headers and handle gzip/deflate/br content.

Node.js (axios, got, fetch)

Use agents with keep-alive; limit max sockets per host.

Set retry policy with exponential backoff and jitter for 502, 503, 504.

Pass a standard User-Agent and Accept headers.

If HTTP/2 is enabled, test a fallback to HTTP/1.1 when errors spike.

Headless browsers (Playwright, Puppeteer)

Use waitUntil: networkidle or a specific selector instead of fixed sleeps.

Enable request interception to block images, video, and fonts.

Rotate user profiles and user agents; persist context per session to look stable.

Throttle navigation rate and randomize small delays between actions.

When the problem is not you

Even stable scrapers see waves of 502s when:

A new deployment at the target misconfigures upstream routes.

CDN edges in a region have issues.

The origin database is slow or down.

In these cases, the best fix is patience plus gentle retries. Watch status pages or social channels for outage notices. If your goal allows it, switch to a mirror domain, a different endpoint, or a cached copy (such as a search engine cache) for a short time.

Security layers and 502

Many sites use CDNs and WAFs like Cloudflare, Akamai, or Fastly. These can show 502 for a range of upstream problems or as a side effect of mitigation.

If you see headers like cf-ray or akamai, you are hitting an edge.

Try alternate routing through another region or POP by changing your proxy location.

Make your requests smaller and less frequent; this often passes automated checks.

If the WAF presents a challenge page or CAPTCHA, do not bypass it unless you have permission. Contact the site owner for access or use an official API.

A practical checklist you can run in five minutes

Open the URL in your browser; confirm the site works.

Cut your concurrency by 80% and add a 1–3 second delay.

Enable retries with exponential backoff and jitter (cap at 3–5 tries).

Swap to a fresh residential proxy or test direct.

Send a modern User-Agent and proper Accept headers; enable gzip.

Set timeouts (connect 5–10s, read 20–30s); enable keep-alive.

Clear cookies for the domain and start a fresh session.

Block images and video if using a headless browser.

Prevent 502 storms with good design

Use a queue with per-host rate limits.

Store success and failure metrics and adapt speed dynamically.

Back off when 5xx rates rise; resume slowly once they drop.

Implement circuit breakers: if a host fails many times, pause that host for a set time.

Add health checks: test a lightweight URL first, then fetch heavy pages.

Cache everything you legally can to avoid re-downloading.

Common mistakes to avoid

Hammering the same endpoint with many threads.

Using a free or public proxy list with bad IP reputation.

Leaving default headers that look like a bot framework.

Ignoring timeouts and letting connections hang forever.

Retrying instantly without backoff, which can trigger more failures.

Spot the difference: 502 vs 503 vs 504

502 Bad Gateway: Edge got a bad response from origin. Often intermittent; retries help.

503 Service Unavailable: Server is overloaded or down for maintenance. Slow down and try later.

504 Gateway Timeout: Edge waited too long for origin. Increase timeout slightly and retry with backoff.

Each of these improves with polite scraping: less load, clean sessions, and smart retries. Good scrapers are fast but kind. If you need to move very quickly, distribute load across time, IPs, and regions. Most of the time, this is how to fix 502 error during web scraping without deep rewrites or risky tricks. A final word: the safest and fastest path is to look like a normal user, move at a human pace, and keep your requests clean. If you follow the steps above, you know how to fix 502 error during web scraping today and avoid most 502s tomorrow.

(Source: https://www.wsj.com/business/energy-oil/ai-data-centers-desperate-for-electricity-are-building-their-own-power-plants-291f5c81)

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