It is not safe to rely on the system's timezone setting. ワーニングが表示される - PHP
PHPのスクリプトを実行すると、
It is not safe to rely on the system's timezone setting. You are *required* to use the date.timezone setting or the date default timezone set() function. In case you uses any those methods and you are still getting this waring, you most likely misspelled the timezone identifier. ...
