White Page after Update.

[AndresJ551]

The site ask for "important updates" and after downloading and installing the updates, it never comes back.

https://cdesk.micronotas.cl/

There are 2 errors on the error_log:

[Sun Nov 26 01:38:56.403251 2017] [:error] [pid 28155] [client 186.136.172.19:52362] FastCGI: server "/var/www/clients/client6/web39/cgi-bin/php5-fcgi-*-443-cdesk.micronotas.cl" stderr: PHP message: PHP Notice: Constant DATE_RFC7231 already defined in /var/www/clients/client6/web39/web/includes/bootstrap.inc on line 258

[Sun Nov 26 01:38:56.403323 2017] [:error] [pid 28155] [client 186.136.172.19:52362] FastCGI: server "/var/www/clients/client6/web39/cgi-bin/php5-fcgi-*-443-cdesk.micronotas.cl" stderr: PHP message: PHP Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) in /var/www/clients/client6/web39/web/sites/all/modules/i18n/i18n_user/i18n_user.module on line 13

The second one I already fixed. This happened twice installing all from scratch, changing the password and then updating drupal.

The system is Ubuntu 16.04.3 with PHP 7.0.25 and MySQL 5.7.20

Thanks in advance.