OPEN
plugins/installer/admintools/admintools.php
GOTO
line 96
FIND
if (!defined('FOF30_INCLUDED') && !@include_once JPATH_LIBRARIES . '/fof30/include.php'))
REPLACE WITH
if (!defined('FOF30_INCLUDED') && !@include_once JPATH_LIBRARIES . '/fof30/include.php')
SAVE & CLOSE