Django static_root in /var/www/... - no permissions to collectstatic

Take ownership of /var/www/app_name/static then put it back the way it was.

$ sudo chown -R myuser:myuser /var/www/app_name/static
$ python manage.py collectstatic
$ sudo chown -R root:root /var/www/app_name/static

I think the best way you should add current user to group www-data