I recently ran the install.py in an Ubuntu 18.04 container, it installed fine but ignored the --python python3 argument. For the record the full command was sudo python3 install.py --production --python python3. Maybe the --production flag overrides the --python flag, I’m not sure. I think it needs to be fixed since Python 2 is EoL’d next year Jan 1 and Frappe and ERPNext both work fine with 3.