Error 500 - "upstream prematurely closed connection while reading response header from upstream"

[vedavrat]

CentOS release 6.9 (Final), 64-bit.
((( Linux 2.6.32-642.13.1.el6.x86_64 #1 SMP Jan 11 2017 x86_64 GNU/Linux )))

Apache + nginx + PHP + MySQL + WordPress.

В логах Apache видно:
"""
15/Jun/2017:11:53:14 "POST /wp-admin/nav-menus.php HTTP/1.0" 500 - "http://vedavrat.org/wp-admin/nav-menus.php" "Mozilla/5.0 (Linux x86_64) OPR/45.0.2552"

2017/06/15 12:02:52 [error] upstream prematurely closed connection while reading response header from upstream, server:vedavrat.org, request:"POST /wp-admin/nav-menus.php HTTP/1.1", upstream:"/wp-admin/nav-menus.php", host:"vedavrat.org", referrer:"http://vedavrat.org/wp-admin/nav-menus.php"

15/Jun/2017:12:26:26 "POST /wp-admin/nav-menus.php HTTP/1.0" 500 - "http://vedavrat.org/wp-admin/nav-menus.php" "Mozilla/5.0 (Linux x86_64) OPR/45.0.2552"
"""

Память увеличивал всем (PHP, nginx, httpd).
Время [timeout] тоже увеличивал всем (PHP, nginx, httpd).

[vedavrat]

И на другие сайты/домены это зло поползло:
"""

Code: Select all

2017/06/19 23:20 [error] 12129#12129: *643286 upstream timed out (110: Connection timed out) while reading response header from upstream, client:146.185.223.245, server:hopak-odesa.ved.bz, request:"GET/HTTP-1.0", upstream:"http://195.123.209.69:8080/", host:"hopak-odesa.ved.bz", referrer:"http://hopak-odesa.ved.bz/" 

"""
В чём причина?

[websystems]

Same problem here, but Presta instead od WP. Did you find any solution?

[exmr]

Всем привет.
Тоже искал концы этой проблемы.
Решил разнеси error логи апача и nginx.
поправил для nginx
/var/log/httpd/domains/мойдомен.nginx.error.log
поправил для apache
/var/log/httpd/domains/мойдомен.httpd.error.log

Перезапустил сервера.
Проблема на домене исчезла.
Не знаю что именно помогло.