I looked at that thread but unfortunately the link for the file that NeHo asks to upload is no longer available.
Yeah, there was an easy way unfortunately i don't have that one saved either.
Re-populate the database with the updated files.
Close the npm/pm2
Download these 2 files and replace them manually in your vm's directory.
Then navigate through console: cd /var/www/html/app/seed or whatever directory you have installed the server
type : nodejs dbseed.js
Start back npm/pm2 and give it a try.
This issue i believe is mainly for no existing admin in the database (the default ones)