[MM3-users] Mailman REST API not available. Please start Mailman core.

Running Debian 4.19.316-1 Python 3.7.3

I am unable to start mailman core

mailman@lists:~$ /opt/mailman/mm/bin/mailman start Usage: mailman start [OPTIONS] Try 'mailman start -h' for help.

Error: A previous run of GNU Mailman did not exit cleanly (stale_lock). Try using --force mailman@lists:~$

I try using --force and it did not work. So how do I start it?

Bottom line: I would like for Mailman core to start when I reboot the server. How can this be achieved please?