The issue: PHP has a new error level E_STRICT, since PHP 5.0. E_STRICT forces you to code clean PHP 5 code Current E_STRICT will most probably become E_FATAL in PHP 6.0 The resolution: Switch E_STRICT on and check your code Typical E_STRICT error - Usage of outdated is_a() function foo(); } ?>]]> Should be now foo(); } ?>]]>