All sites are down in Plesk: Syntax error on line 31 of /etc/httpd/conf.d/php.conf: Invalid command 'php_value'

Symptoms

• Apache is in Failed state in Plesk, the following error is displayed in Plesk Home page:

  PLESK_ERROR: New configuration files for the Apache web server were not created due to the errors in configuration templates: AH00526: Syntax error on line 31 of /etc/httpd/conf.d/php.conf: Invalid command 'php_value', perhaps misspelled or defined by a module not included in the server configuration.

• System PHP was installed manually from OS repositories using system package manager:

  # tail /var/log/yum.log
  Nov 11 02:47:19 Installed: libzip-0.10.1-8.el7.x86_64
  Nov 11 02:47:19 Installed: php-common-5.4.16-48.el7.x86_64
  Nov 11 02:47:20 Installed: php-cli-5.4.16-48.el7.x86_64
  Nov 11 02:47:20 Installed: php-pdo-5.4.16-48.el7.x86_64
  Nov 11 02:47:20 Installed: t1lib-5.1.2-14.el7.x86_64
  Nov 11 02:47:20 Installed: php-gd-5.4.16-48.el7.x86_64
  Nov 11 02:47:20 Installed: php-mysql-5.4.16-48.el7.x86_64
  Nov 11 02:47:20 Installed: php-5.4.16-48.el7.x86_64
  Nov 11 02:47:20 Installed: php-ldap-5.4.16-48.el7.x86_64
  
  # history | grep php
  yum install php php-mcrypt php-cli php-gd php-curl php-mysql php-ldap php-zip php-fileinfo

Cause

php package in OS repositories includes incorrect syntax in /etc/httpd/conf.d/php.conf: php_value parameters are included without <IfModule mod_php5.c> tags:

# tail -5 /etc/httpd/conf.d/php.conf
# Apache specific PHP configuration options
# those can be override in each configured vhost
#
php_value session.save_handler "files"
php_value session.save_path "/var/lib/php/session"

Resolution

1. Connect to the server via SSH
2. Create a backup of the configuration file:

   # cp /etc/httpd/conf.d/php.conf{,.orig}

3. Edit /etc/httpd/conf.d/php.conffile in any text editor and edit the syntax to include the <IfModule mod_php5.c> tags:
   BEFORE:

   CONFIG_TEXT: php_value session.save_handler "files"
   php_value session.save_path "/var/lib/php/session"

   AFTER:

   CONFIG_TEXT: <IfModule mod_php5.c>
   php_value session.save_handler "files"
   php_value session.save_path    "/var/lib/php/session"
   </IfModule>