Enable OPCache on Ubuntu: Alternative to APC Cache
If you are using PHP 5.5, it is not supported by APC Cache. For reference, see PHP Bug #65731 PHP 5.5 comes with it's own opcode cache which can be enabled with the following steps: 1. Enable opcache in php.ini sudo nano /etc/php5/apache2/php.ini Look for the line: ;opcache.enable=0 And replace with: opcache.enable=1 2. Enable the php mod sudo php5enmod opcache sudo service apache2 restart If you are using PHP lower than 5.5, then you can still use APC. Just run this line in the terminal to install APC. sudo apt-get install php-apc