strtotime(): 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 'Europe/Helsinki' for 'EET/2.0/no DST' instead

[Date]
; Defines the default timezone used by the date functions
; http://www.php.net/manual/en/datetime.configuration.php#ini.date.timezone
date.timezone = Europe/Amsterdam

date_default_timezone_set('Europe/Amsterdam');