Yes you are absolutely right! After I modified according to your suggestion the error was resolved. I still don't know why I had this issue since I have been using this bash script to start the server for months, and I have never experienced problem. The trouble started today.
(env) **jianwu@django-hdserver** : **~/HD_website/website** $ cat start_modwsgi.sh
#!/bin/sh
#Configuration on how to start the server
python manage.py runmodwsgi \
--server-root /etc/wsgi-port-80 \
--user www-data --group www-data \
--port 80 --setup-only \
--https-only \
--https-port 443 \
--ssl-certificate-file "/etc/letsencrypt/live/www.dimsum.dk/fullchain.pem" \
--ssl-certificate-key-file "/etc/letsencrypt/live/www.dimsum.dk/privkey.pem" \
--server-name 'www.dimsum.dk'
#Starting the server
sudo /etc/wsgi-port-80/apachectl restart