Error, bench install-app missing

ubuntu@ip-172-31-27-142:~/frappe-bench/sites$ bench install-app
Usage: bench [OPTIONS] COMMAND [ARGS]…

Error: No such command “install-app”.

I’ve followed the steps in the guide to setup v4 but when i reach this step, i cannot get pass.

As you have said it that you are on v4, the command for v4 should be:

bench frappe --install_app APP-NAME

I’ve managed to get it to work with bench frappe sitename --install_app erpnext

Just a note, the insturctions on https://github.com/frappe/bench is written as bench install-app erpnext under “Setting up ERPNext”