Error 502 Bad Gateway appeared. And some menu links disappeared and I'm not able to edit anything on the site through the admin.
I contacted wordpress and according to them the error is:
PHP Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 262144 bytes) in /srv/htdocs/wp-content/plugins/visualcomposer/visualcomposer/Framework/Application.php on line 84