What Is Proxy Error 502? How to Fix 502 Bad Gateway?

When you see 502 Bad Gateway while using a proxy (Proxy), it means:

The proxy server did not receive a “valid response” from the upstream server.

Simply put — the request was sent, but the proxy received an abnormal response from the target website, so it returned 502.

What Is Proxy Error 502?

502 Bad Gateway

It means:
When a server acts as a “gateway” or “middleman,” it receives an invalid response from the upstream server.

In a proxy scenario, the request path is typically:

Your device → Proxy server → Target website → Proxy → You

When the target website returns an abnormal response, or communication between the proxy and the target fails, a 502 error occurs.

Common Causes

1. The Target Website Rejected the Request

· IP blocked

· Request frequency too high

· Abnormal request headers

· Flagged as a bot by risk control systems

This is very common in data scraping and account operations.

2. The Proxy Server Is Unstable

· Node offline

· Connection timeout

· Upstream channel issues

· Poor proxy pool quality

If you use free or low-quality proxies, the chance of encountering 502 errors increases significantly.

3. The Target Server Is Down

· Temporary website maintenance

· Server overload

· CDN failure

In many cases, refreshing a few times will resolve the issue.

4. Request Timeout

If the target website responds too slowly, the proxy may time out and return a 502 error.

How to Quickly Identify the Problem

1. Access the Target Website Using Your Local IP

· If it opens → The website is fine

· If it doesn’t → The website itself may be experiencing issues

2. Switch to Another Proxy Node

· If the new node works → The original node was the issue

· If none work → Your IP may have been blocked

3. Reduce Request Frequency

· In scraping scenarios, try adding delays between requests

4. Check Request Headers

· Missing User-Agent

· Abnormal cookies

502 in Different Scenarios

▍502 in Browser Access

Usually caused by:

· Website server issues

· CDN problems

For example, when using a CDN like Cloudflare, backend downtime may directly trigger a 502 error.

▍502 in Crawlers/Scripts

Usually caused by:

· Poor proxy quality

· Target site risk control

· IP blacklisted

▍502 in an Nginx Environment

If you deploy your own server using Nginx, a 502 error usually indicates a connection problem between the reverse proxy and the backend service. Common causes include incorrect upstream configuration, the backend service not running properly, or the target port not listening successfully, preventing Nginx from obtaining a valid response.

Similar Error Codes

Many people confuse the following:

Summary

502 Bad Gateway means the proxy or gateway successfully sent the request but did not receive a valid response from the upstream server. The issue usually lies in unstable proxy nodes, blocked IPs, target website rejection, server failure, or communication interruptions. When encountering a 502 error, you should first check proxy quality, request frequency, and the target website’s status rather than suspecting your local device.

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