remove django-userena
install django-userena-ce

upgrade packages:
 pip3 list --format=legacy|grep django-|grep django|sed -e 's/django-\(.*\) .*/\1/'|while read i; do pip3 install -U django-$i; done
 pip3 list --format=legacy|grep djangocms-|grep djangocms|sed -e 's/djangocms-\(.*\) .*/\1/'|while read i; do pip3 install -U djangocms-$i; done

##update /usr/local/lib/python3.5/dist-packages/guest/models.py, add parameters to ForiegnKey: on_delete=models.CASCADE
If /usr/local/lib/python3.5/dist-packages/guest/ exists from a previous installation, delete it.

./manage.py collectstatic

./manage.py makemigrations --merge 
./manage.py migrate