Using this as reference, this is how I resolved the following Code Igniter APC Cache error: Fatal error: Call to undefined function apc_fetch() in D:\xampp\www\com\xxx\system\libraries\Cache\drivers\Cache_apc.php on line 41: I looked at this doc: Found this section… Installation on Windows Server Warning: You cannot install APC and Zend Optimiser on the same server. You should.. read more →