If you encounter such issue, after some software upgrade. It might be
cuased by unsupported application installed.
Access to your SSH via root user.
Type below command
nginx -t
> It will show what is causing Nginx can start. In most recently case
we saw from our users was the modsecurity version rules inside
Directadmin. If this was the case, you will need to disable the Mod Rules
inside the Directadmin panel. And restart your Nginx again and it should
start now.
Type below command after you disable the Mod Rules.
service nginx start
If it still don't work, don't worry contact support and we will have it
verify and fix for you.