Error while reading response header from upstream

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Hi, I get WordPress critical fallback error in backend when I click on plugin settings under NGINX. Under Apache not! I use parallel “EasyUpdateManager”, when EUM is deactivated than I get plugin settings and options for WP-Optimize, when EasyUpdateManager is parallel active than not. In error log is following entry:

>>
WP_Optim” while reading response header from upstream, client: 84.178.xx.xxx, server: xxxxx, request: “GET /wp-admin/admin.php?page=WP-Optimize HTTP/1.1”, upstream: “fastcgi://unix:/var/lib/php5-fpm/web74.sock:”, host: …
<<

So, it’s looks like that exist an php misscoding in plugin sources, the reason is not the fast-cgi buffer size in NGINX. Maybe fit the php error in EasyUpdateManager.

WordPress 5.3.2, PHP 7.2.8 FPM, NGINX 1.15.2
EasyUpdateManager free version latest,
WP-Optimize free version latest

Thanks attention and research