- Plesk 11.x for Linux
- Plesk 12.0 for Linux
- Plesk 12.5 for Linux
A site active users are dropped and the site page gets unavailable.
PHP FPM handler served by Nginx is used in Plesk > Domains > example.com > PHP Settings.
/var/www/vhosts/system/example.com/logs/proxy_error_logfile the following entries may be observed:
PLESK_INFO: [error] 4459#0: *881104 connect() to unix:/var/www/vhosts/system/example.com/php-fpm.sock failed (11: Resource temporarily unavailable) while connecting to upstream, client: 203.0.113.2, server: example.com, request: "GET /in/?u=cm9ja2VuaW5uYW5hbm5lfGlufDI1MHwxfDN8fG5vfDV8dW5kZWZpbmVk HTTP/1.1", upstream: "fastcgi://unix:/var/www/vhosts/system/example.com/php-fpm.sock:", host: "example.com"
This is a software issue #PPPM-2357 that will be fixed in future product updates.
By default, interaction between NGINX and PHP-FPM is configured to use UNIX sockets. Sites with high load exceed OS limitations. However, there are no options in Plesk GUI to change from UNIX socket to TCP at the moment. And manual changes in configuration files for domains are getting overwritten by Plesk.
As a workaround, switch the domain PHP handler to PHP FPM served by Apache:
- Log into Plesk.
- Open Domains > example.com > PHP Settings.
- Select FPM application served by Apache and click OK.