Chyba v logu PHP

[Thu Nov 29 09:50:37.780240 2018] [:error] [pid 14405] [client] PHP Warning:  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 the timezone 'UTC' for now, but please set date.timezone to select your timezone. in /var/www/html/testlink/config.inc.php on line 1856, referer: 

Add to the config „config.inc.php“ file this code

  date_default_timezone_set(<time_zone> např. "Europe/Prague");