Hi!
I added another config to nginx and when i try to systemctl restart nginx (CentOS7) I get the error:
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
It looks like something else is managing the currently running nginx instance.