myVesta

Shows: 502 Bad Gateway
nginx

Also, i receive an email from server:
Cron <admin@mysitel> sudo /usr/local/vesta/bin/v-update-sys-vesta-all
Error: vesta update failed
Error: vesta-nginx update failed
Error: vesta-php update failed

Does it change something on the session profile?

Probably your server has small RAM.
Restarting server will bring back all services.