Ufw don't working ERROR: not enough args

I have installed ufw and gufw in Ubuntu 18.04 with XFce4.12 environment. I was exploring its configurations, then I looked for some tutorials to configure it and when I run sudo ufw it returns this to me:

ERROR: not enough args

Then I run:

$ sudo ufw enable
Traceback (most recent call last):
  File "/usr/sbin/ufw", line 115, in <module>
    datadir=datadir)
  File "/usr/lib/python3/dist-packages/ufw/frontend.py", line 165, in __init__
    datadir=datadir)
  File "/usr/lib/python3/dist-packages/ufw/backend_iptables.py", line 51, in __init__
    rootdir=rootdir, datadir=datadir)
  File "/usr/lib/python3/dist-packages/ufw/backend.py", line 54, in __init__
    self._get_defaults()
  File "/usr/lib/python3/dist-packages/ufw/backend.py", line 288, in _get_defaults
    for line in orig:
  File "/usr/lib/python3.6/codecs.py", line 321, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xac in position 4: invalid start byte

I can no longer start it, I have uninstalled and reinstalled it and it remains the same, any help please?