Server Error (5xx)
HTTP 502 β 502 Bad Gateway
The server, while acting as a gateway or proxy, received an invalid response from the inbound server it accessed.
Common Causes & Diagnoses
- β’Backend Node.js / Python PM2 process crashed or is down.
- β’Nginx proxy_pass pointing to wrong internal port.
- β’Upstream server ran out of memory (OOM killed).
Spesifikasyon & Kategori
Status Code:502
Category:Server Error (5xx)
RFC Standard:RFC 9110 / HTTP/1.1 & HTTP/2
Multi-Language Code Implementations
How to Handle, Return & Test HTTP 502
Status: 502 502 Bad Gateway
server.js / handler.ts
// Express.js Server Response
app.get('/api/resource', (req, res) => {
// Returning 502 502 Bad Gateway
return res.status(502).json({
error: '502 Bad Gateway',
statusCode: 502,
timestamp: new Date().toISOString()
});
});
// Client-side fetch error check
const response = await fetch('/api/resource');
if (response.status === 502) {
console.warn('Received HTTP 502 502 Bad Gateway');
}π‘ Pro Tip: Ensure appropriate error handling middleware or proxy interceptors are enabled so client applications receive structured JSON responses for HTTP 502.
How to Fix / Practical Code Solutions
Check PM2 or Systemd Backend Service
Verify if backend application process is running.
pm2 status pm2 logs backend systemctl status nginx
Other Popular HTTP Status Codes
Frequently Asked Questions
Common Questions About HTTP 502 to RFC Standard
Everything you need to know regarding specifications, syntax, and security best practices.
The server, while acting as a gateway or proxy, received an invalid response from the inbound server it accessed. In Turkish: Ters proxy (Nginx, Cloudflare), arka plandaki uygulama sunucusundan geçersiz yanıt aldı.