One of my server recently rebooted by itself, but Nginx refused to start when it came back online.

Manually trying to restart Nginx alternately threw the following errors

To add, I noticed that Plesk had overwritten my modified nginx.conf with it’s default copy. Replacing it with the modified version did not fix the issue, neither did troubleshooting the first error bring any luck.

The second line is where I struck gold, the server crash triggered Plesk to forget that it ever used Nginx and disable it from even starting, I issued the following command at shell to get it to start.

issuing a service start command to nginx after this finally started nginx.

 

credits to abdi on the Odin forums for this find: original thread