The HTTP 502 Bad Gateway error means the server acting as a middleman (a proxy or gateway) received an invalid response from the server upstream (the one holding the actual data).
Essentially, the servers are failing to talk to each other correctly. While this is primarily a server-side headache, there are things you can do right now.
🏃 Quick Fixes for Users
Before panicking, try these simple client-side troubleshooting steps:
Refresh the Page: It sounds basic, but many 502s are temporary network glitches. Hit F5 or the refresh icon.
Clear Browser Cache: Outdated or corrupted cache and cookies can sometimes interfere. Give your browser a fresh start.
Check Your Network/VPN: If you are using a VPN, proxy, or strict firewall, try disabling it temporarily. If the site loads, the issue is on your network’s end.
Test Availability: Use a free online tool to check if the website is down for everyone or just for you.
👷 Action Plan for Server Admins
If the 502 is happening on your watch, the problem is likely in your network path, load balancing, or backend application. Get straight to these checks:
1. The Logs are King
Immediately review your server logs (gateway and backend) for specific timeout messages or rejected connections. The logs will pinpoint which connection failed.
2. Inspect the Backend
Application Health: Is the application running correctly? Is it crashing or running out of memory?
Timeouts: Check your application's response time. If it's too slow, the gateway or load balancer might be prematurely closing the connection. Increase the keep-alive or request timeout settings if necessary.
3. Review Network Components
Load Balancer: Ensure its health checks are functioning and correctly routing traffic only to healthy instances.
Firewalls: Are any firewall rules blocking communication between the gateway/proxy and the backend application servers?
DNS: Verify that the domain name system (DNS) settings are resolving correctly to the right internal IPs.
A 502 means an invalid handshake. By checking the logs and verifying the path from the gateway to the backend, you can usually identify and fix the communication breakdown quickly.
