By Ruz
I recently upgraded my DigitalOcean droplet from Ubuntu 22.04 to Ubuntu 24.04 LTS. After the upgrade, nginx started returning 502 Bad Gateway errors for all my sites.
I have checked the following so far:
- nginx service is running fine (systemctl status nginx shows active)
- PHP-FPM 8.3 is running and listening on the correct socket
- The upstream Node.js app responds correctly when I curl localhost:3000 directly
- No permission issues on socket files
Here is the relevant error from /var/log/nginx/error.log:
connect() failed (111: Connection refused) while connecting to upstream
My nginx config uses proxy_pass to forward requests to a Node.js application running on port 3000. The app works fine when accessed directly but nginx cannot proxy to it.
I suspect something changed with systemd socket activation or AppArmor profiles in Ubuntu 24.04 Noble Numbat. Has anyone else experienced this issue after upgrading?
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Heya,
the connect() failed (111: Connection refused) while connecting to upstream error almost always means an issue with the app behind the reverse proxy. Check the error logs of the app. It can be a broken function or something.
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