Reading the error log: why the 502 happened
Find the line that says why Nginx got nothing from the upstream, read it field by field, and tell a refused connection from one closed too early and from a socket the worker may not open.
22 minutesTechnical content last reviewed on 14 Sept 2026
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What this lesson builds
- Serving a site and putting an application behind Nginx
- Saying what an output proves, and what it leaves open
- Narrowing an unknown failure to one component