It is not safe to rely on the system's timezone settings.

访问Yii框架自带的例子系统时，页面打印500错误:

date() [<a href='function.date'>function.date</a>]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'UTC' for '8.0/no DST' instead

经查和试验解决方案为：

在php.ini中设置时区：
date.timezone = "Asia/Shanghai"

或者在网页开头中加入：
<?php
date_default_timezone_set("PRC");
?>