Websites on PHP-FPM shows 502 Bad Gateway or 504 Gateway Timeout: Reloading in progress

Symptoms

• Websites or site's preview that use php-fpm show following errors: 502 Bad Gateway or 504 Gateway Timeout;
• In /var/log/php-fpm/error.log or similar, the following record can be found:

  CONFIG_TEXT: NOTICE: Reloading in progress ...

  OR

  CONFIG_TEXT: AH01079: failed to make connection to backend: httpd-UDS / AH02454: FCGI: attempt to connect to Unix domain socket failed

  Or any similar error.

Cause

php-fpm service is hanged or down.

Resolution

Using Plesk interface

Go to Tools & Settings > Services Management and restart the required PHP-FPM handler.

Using SSH connection.

1. Connect to the server via SSH;
2. Restart PHP-FPM service:

   # service php-fpm restart

Note: Service may be plesk-php56-fpm, plesk-php70-fpm and etc. It depends on handler that is being used for domain. It can be