title: Datetimezone Error for website
body: <p>When I try to enter the site a white page appears</p>
  
  <pre><code>[Mon May 21 21:06:21.190385 2018] [:error] [pid 13340] [client 89.64.24.10:19041] PHP Notice:  Undefined property: object::$default_timezone in /var/www/html/frontend/lib/common.php on line 92
  [Mon May 21 21:06:21.193439 2018] [:error] [pid 13340] [client 89.64.24.10:19041] PHP Notice:  date_default_timezone_set(): Timezone ID '' is invalid in /var/www/html/frontend/lib/common.php on line 92
  [Mon May 21 21:06:21.193476 2018] [:error] [pid 13340] [client 89.64.24.10:19041] PHP Notice:  Undefined property: object::$default_timezone in /var/www/html/frontend/lib/common.php on line 93
  [Mon May 21 21:06:21.193603 2018] [:error] [pid 13340] [client 89.64.24.10:19041] PHP Fatal error:  Uncaught Exception: DateTimeZone::__construct(): Unknown or bad timezone () in /var/www/html/frontend/lib/common.php:93\nStack trace:\n#0 /var/www/html/frontend/lib/common.php(93): DateTimeZone-&gt;__construct('')\n#1 /var/www/html/frontend/htdocs/index.php(4): include('/var/www/html/f...')\n#2 {main}\n  thrown in /var/www/html/frontend/lib/common.php on line 93
  </code></pre>
  
  <p>time zone line 92-93-94-95 (common.php)</p>
  
  <pre><code>date_default_timezone_set($CFG-&gt;default_timezone);
  $dtz = new DateTimeZone($CFG-&gt;default_timezone);
  $dtz1 = new DateTime('now', $dtz);
  $CFG-&gt;timezone_offset = $dtz-&gt;getOffset($dtz1);
  </code></pre>