reload nginx

I am getting the following error and my app stops working:
    2020/07/12 14:32:03 [error] 45625#45625: *10918 upstream sent too big header while reading response header from upstream, client:, server:, request: “POST /app/mg/posts HTTP/2.0”, upstream: “fastcgi://unix:/run/php/php-fpm.sock:”, host: “”, referrer: “”
How do I fix this error for Nginx web server running on Linux or Unix-like systems?
[continue reading…]