I got this error on my website and suddenly it was down. With the following command I was able to debunk the issue:
/usr/sbin/nginx -c /etc/nginx/nginx.conf
This resulted in the following error
nginx: [emerg] invalid number of arguments in "location" directive in /etc/nginx/sites-enab led/mysite.com:56
So I knew I made a mistake in my configuration that caused the error.