==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.4.0
- Deployed with iRedMail Easy or the downloadable installer?Installer
- Linux/BSD distribution name and version: Centos 7.9.2009
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx):Nhinx
- Manage mail accounts with iRedAdmin-Pro?No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====
Trying to remove a subscriber from a mailing list with cli using maillist_admin.py using mlmmj v3.1.1
Receive error message:

Traceback (most recent call last):
  File "maillist_admin.py", line 234, in <module>
    qr = backend.remove_subscribers(mail=mail, subscribers=_subscribers)
AttributeError: module 'bk_iredmail_sql' has no attribute 'remove_subscribers'

Any advice welcome