I installed nginx on a rasp pie yesterday.
At that time, when the IP address of Raspberry Pi was entered in the browser, the default page of Nginx was displayed.

But if I enter the IP address of Raspberry Pi in the browser after shutting down and restarting Rasp Pi, Internal Server Error is displayed.

Try it

I checked where the error is, but there is no error.
Does this mean that it is not an nginx error?

(lab_app) root @ raspberrypi:/var/log/nginx # tail -n 100 error.log
2019/12/03 08:21:21 [notice] 2477 # 2477: signal process started