Zend Optimizer asks for stop the server. If you use W:\ in config it will not find the files to modify when you stop server, istead use real path of these files: Download the Zend Optimizer exe (http://www.zend.com/free_download/optimizer) Start the server Run the exe Select Apache 2.x in the Web Server Options php.ini's destination folder should be D:\UniServer\udrive\usr\local\php Root folder should be D:\UniServer\udrive\usr\local\apache2 Only doing this it works for me. Regards