j'ai retrouvé au moment du plantage j'ai eu plein de warning de ce style
[Mon May 28 10:13:50 2018] [warn] [client 80.12.41.165] mod_fcgid: stderr: PHP Parse error: syntax error, unexpected T_OBJECT_OPERATOR in /vdir/www.byvad.com/var/www/vhosts/www.byvad.com/web/client/plugins/ganalytics/Ganalytics.class.php on line 539