ERR_TOO_MANY_REDIRECTS on Nginx
Why it happens on Nginx
A 'return 301 https://$host$request_uri' block inside the HTTPS server block sends HTTPS traffic back to itself, producing an infinite loop behind a TLS-terminating proxy.
The fix on Nginx
Keep the redirect only in the port 80 server block, and behind a proxy redirect on $http_x_forwarded_proto = http rather than on the port.
Is ERR_TOO_MANY_REDIRECTS happening on your domain?
The uptime probe returns the full redirect chain, so you can see the exact two URLs bouncing off each other instead of inferring it from behaviour.
Free, no signup. Runs from outside your network, which is the only way to tell a server fault from a local one.
If that didn't fix it
Nginx has its own failure mode, but ERR_TOO_MANY_REDIRECTS has a wider set of causes that apply everywhere. The most common one overall is: the cdn forwards to the origin over http while the origin redirects all http to https — an infinite loop.
All causes and fixes for ERR_TOO_MANY_REDIRECTS