When moving to nginx for the first time I had the lovely idea to put all 8 sites from my personal centos 6.5/apache 2 server into technology I’ve never used before.
After a lot of debugging including some Tiger Woods Bobble Head debugging, I found a pattern. When load-scripts was pulling in a bunch of libraries it would just stop loading at seemingly random points. Error logs were showing permission errors to /var/lib/nginx. A light came on, I had recently changed the default user www-data; line in nginx.conf to user ftpuser; in an attempt to have WordPress and my ftp user able to write to the server.
Switched it back to www-user and everything was fixed. Now I just need to really dive in to users/groups and permissions on nginx and do it the right way.