net::ERR_INCOMPLETE_CHUNKED_ENCODING nginx
You might want to check if the user that is running the Nginx worker owns the directory /var/lib/nginx (or /var/cache/nginx in some distros).
I've learned that when you give a response too big for Nginx, it uses this directory to write as a working directory for temporary files. If the worker process cannot access it, Nginx will terminate the transmission before it completes, thus the error INCOMPLETE_CHUNKED_ENCODING.
Bumped into this issue on AWS and found that adding a few proxy_buffer directives to the site config file fixed the issues:
server { ... location / { ... proxy_buffers 8 1024k; proxy_buffer_size 1024k; }}
For me, the solution was what DfKimer recommended, but instead of /var/lib/nginx it was /var/cache/nginx.