ALLOWED_HOSTS and Django
If Django says:
Invalid HTTP_HOST header: 'bla-bla-bla.bla-bla-vla.com'. You may need to add u'bla-bla-bla.bla-bla-vla.com' to ALLOWED_HOSTS
then you need to add bla-bla-bla.bla-bla-vla.com, literally (or using a dot as a wildcard) to ALLOWED_HOSTS
(docs).
Then reload Apache2 (not restart, reload) to verify changes have applied.
As I said in comments :
First option :
You have to write : ALLOWED_HOSTS=["bla-bla.com", "localhost", "127.0.0.1"]
in settings.py file
Then, you just have to restart your server with :
sudo reboot
Or easily reload or restart apache2 service
service apache2 reload
or service apache2 restart
It should work now ;)