Why Caddy Gives 502 When the Backend Works Fine by IP
A 502 usually means the browser-to-Caddy leg worked and the Caddy-to-upstream leg did not.
502
The Intermittent 502 That Appears Only After a Connection Has Been Idle
Keepalive timeout mismatches can fail a request even while proxy and backend are otherwise healthy.
Inside a Caddy Container, localhost Is Caddy — Not Your App
The most common Docker reverse-proxy mistake is technically valid networking aimed at the wrong namespace.
Why handle_errors Does Not Catch the 502 Your Upstream Returned
A proxied 5xx status is a response, not automatically a Caddy handler error.
Cloudflare Tunnel Reaches Caddy but Still Returns 502
The failing TLS identity may be on the Cloudflare-to-origin leg rather than in Caddy's upstream proxy.