nginx returning 502 after update ubuntu

After installing the Ubuntu update on the server, nginx returns 502 when attempting to access an application deployed to the Tomcat.

In this case, the Tomcat settings were not changed, when I tried to connect directly-it works successfully. Port 8080 is open in the firewall.

Nginx settings were not changed. At the same time when restarting the server nginx can easily reach the server for some time all nginx quietly redirects the request to the Tomcat. There is no access to nginx configuration, but it has not changed. I could n't find a workaround in Internet. Can someone help here?