Traceback (most recent call last):
  File "/usr/sbin/ufw", line 95, in <module>
    ui = ufw.frontend.UFWFrontend(pr.dryrun)
  File "/usr/lib/python3/dist-packages/ufw/frontend.py", line 153, in __init__
    self.backend = UFWBackendIptables(dryrun)
  File "/usr/lib/python3/dist-packages/ufw/backend_iptables.py", line 45, in __init__
    ufw.backend.UFWBackend.__init__(self, "iptables", dryrun, files)
  File "/usr/lib/python3/dist-packages/ufw/backend.py", line 88, in __init__
    nf_caps = ufw.util.get_netfilter_capabilities(self.ip6tables)
  File "/usr/lib/python3/dist-packages/ufw/util.py", line 734, in get_netfilter_capabilities
    raise OSError(errno.ENOENT, out)
OSError: [Errno 2] ip6tables v1.4.12: can't initialize ip6tables table `filter': Address family not supported by protocol
Perhaps ip6tables or your kernel needs to be upgraded.