« MODx Parse Error »

MODx encountered the following error while attempting to parse the requested resource:
« PHP Parse Error »
PHP error debug
  Error: strftime(): 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 'Asia/Tokyo' for 'JST/9.0/no DST' instead 
  Error type/ Nr.: Warning - 2 
  File: /www/netrevo/assets/snippets/ditto/classes/ditto.class.inc.php 
  Line: 294 
  Line 294 source: $placeholders['date'] = strftime($dateFormat,$timestamp);  
Parser timing
  MySQL: 0.0008 s(9 Requests)
  PHP: 0.0196 s 
  Total: 0.0204 s