2019-09-21 00:24:39 DEBUG1: Traceback (most recent call last):
  File "/usr/lib/python3.7/site-packages/firewall/server/decorators.py", line 53, in handle_exceptions
    return func(*args, **kwargs)
  File "/usr/lib/python3.7/site-packages/firewall/server/firewalld.py", line 94, in start
    return self.fw.start()
  File "/usr/lib/python3.7/site-packages/firewall/core/fw.py", line 515, in start
    self._start()
  File "/usr/lib/python3.7/site-packages/firewall/core/fw.py", line 480, in _start
    self.zone.apply_zones(use_transaction=transaction)
  File "/usr/lib/python3.7/site-packages/firewall/core/fw_zone.py", line 173, in apply_zones
    raise error
  File "/usr/lib/python3.7/site-packages/firewall/core/fw_zone.py", line 87, in _first_except
    f(name, *args, **kwargs)
  File "/usr/lib/python3.7/site-packages/firewall/core/fw_zone.py", line 772, in add_service
    self._service(True, _zone, service, zone_transaction)
  File "/usr/lib/python3.7/site-packages/firewall/core/fw_zone.py", line 1762, in _service
    helpers = self.get_helpers_for_service_modules(svc.modules, enable)
  File "/usr/lib/python3.7/site-packages/firewall/core/fw_zone.py", line 836, in get_helpers_for_service_modules
    "'%s' is not available" % helper.module)
firewall.errors.FirewallError: INVALID_HELPER: 'nf_conntrack_netbios_ns' is not available

2019-09-21 00:24:39 ERROR: INVALID_HELPER: 'nf_conntrack_netbios_ns' is not available