/config /nginx/proxy-pass-trailing-slash

nginx proxy_pass with and without a trailing slash

updated 2026-10-20

tool: nginx
file: nginx.conf (location context)
key: proxy_pass
type: URL: protocol://host[:port][/uri]
default: none

Whether proxy_pass has a URI part decides what path the backend receives. Without a URI (proxy_pass http://127.0.0.1:3000;) nginx forwards the request URI unchanged. With a URI, even just /, nginx replaces the part of the request URI that matched the location prefix with that URI.

The four cases, with real requests

A Node.js backend prints the path it receives; nginx proxies to it from four locations:

bash

mkdir -p logs temp
cat > backend.js <<'EOF'
const s = require("http").createServer((req, res) => res.end(`backend saw ${req.url}\n`));
s.listen(3901, "127.0.0.1");
setTimeout(() => process.exit(0), 4000);
EOF
cat > nginx.conf <<'EOF'
pid logs/nginx.pid;
events {}
http {
  access_log off;
  server {
    listen 127.0.0.1:3902;
    location /no-slash/   { proxy_pass http://127.0.0.1:3901; }
    location /with-slash/ { proxy_pass http://127.0.0.1:3901/; }
    location /api/        { proxy_pass http://127.0.0.1:3901/v2/; }
    location /mixed       { proxy_pass http://127.0.0.1:3901/; }
  }
}
EOF
node backend.js &
nginx -p . -c nginx.conf -e logs/error.log &
sleep 1
for path in /no-slash/users /with-slash/users /api/users /mixed/users; do
  printf '%-18s -> ' "$path"; curl -s "http://127.0.0.1:3902$path"
done
nginx -p . -c nginx.conf -e logs/error.log -s stop

Output

/no-slash/users    -> backend saw /no-slash/users
/with-slash/users  -> backend saw /users
/api/users         -> backend saw /v2/users
/mixed/users       -> backend saw //users

Rule of thumb

location	proxy_pass	Request	Backend receives
/app/	http://b:3000	/app/users	/app/users
/app/	http://b:3000/	/app/users	/users
/app/	http://b:3000/v2/	/app/users	/v2/users
/app	http://b:3000/	/app/users	//users (keep slashes consistent)

Inside regular-expression locations a URI part is not allowed at all; see proxy_pass cannot have URI part.

Sources

errors · nginxnginx: "proxy_pass" cannot have URI part in location given by regular expressionnginx rejects proxy_pass http://host/path/ inside a regex location, named location, if or limit_except. Remove the URI part and change the path with rewrite.glossary · nginxWhat is a reverse proxy?A reverse proxy is a server in front of your applications that receives client requests and forwards them to backends, adding TLS, caching and balancing.cheat sheets · nginxnginx cheat sheet: commands, server blocks, locations and proxyingnginx cheat sheet: test and reload, logs, server blocks, location matching order, reverse proxy headers, HTTPS redirects, static files and caching headers.

The four cases, with real requests

Rule of thumb

Sources

Related pages