This is a php server issue.
The host should be able to update the php.ini file for you to set the default timezone to prevent that error from occurring. It happens if the default time zone is not set in the php.ini.
alternately, you can add the following code to the page to set the time zone:
The list of valid timezones is here...
it is best to have the host fix it in the php.ini file though so you don't keep running into it in other places.