Gunicorn socket error with Ubuntu 18.04 and Django

I am following this tutorial:How To Set Up Django with Postgres, Nginx, and Gunicorn on Ubuntu 18.04

I am at the point of checking for the gunicorn socket file:

sudo systemctl status gunicorn.socket

and I get the following error:

Failed to dump process list, ignoring: No such file or directory
β—� gunicorn.socket - gunicorn socket
   Loaded: loaded (/etc/systemd/system/gunicorn.socket; enabled; vendor preset: enabled)
   Active: active (listening) since Sun 2019-05-05 21:45:34 UTC; 13s ago
   Listen: /run/gunicorn.sock (Stream)
   CGroup: /system.slice/gunicorn.socket

What file or directory does it refer to ?