We have a synchronisation script running with the REST API from WooCommerce. This script is running for years. But suddenly it received gateway errrors
/var/log/nginx/error.log, the following error messages appeared
2022/08/03 22:41:19 [error] 1233#33321: *323108 upstream sent too big header while reading response header from upstream, client: 10.0.0.1, server: www.example.com, request: "POST /wp-json/wc/v3/products/1234/variations/batch HTTP/1.1", upstream: "fastcgi://unix:/tmp/example.com.sock:", host: "www.example.com"
It seems PHP is sending debug information over the FASTCGI headers.
This isn't desirable.
To fix it, disable it in php.ini. (it's on by default. WHY!?)
fastcgi.logging = 0
Btw. these errors/warnings are from low quality wordpress-plugins. (which cannot be replaced directly)