Install and configure uwsgi

apt install uwsgi
apt install uwsgi-plugin-python3
ln -s /home/dev/python-flask-demo/config/demo-uwsgi.ini /etc/uwsgi/apps-enabled/demo-uwsgi.ini
service uwsgi restart

If there is a problem you might find help by looking at the log file:

/var/log/uwsgi/app/demo-uwsgi.log

I got the following error "Fatal Python error: init_fs_encoding: failed to get the Python codec of the filesystem encoding"

I had make the home directory of the dev user to be world readable, that solved the problem:

chmod +r /home/dev/