date(): 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.

Set following value in php.ini file

date.timezone = 'Asia/Kolkata'

It depends on your timezone. Set your timezone in php.ini
You may face this error if this line is commented.

Restart Apache and try again.