sudo add-apt-repository зависает без ошибок Ubuntu 19.04

Всякий раз, когда я пытаюсь запустить sudo add-apt-repository ppa:docky-core/ppa (для любого ppa, а не только для этого), он просто зависает бесконечно, без каких-либо ошибок, даже с флагом -m. После того, как я завершаю его с помощью Ctrl + C, он показывает следующее:

^CTraceback (most recent call last):
  File "/usr/bin/add-apt-repository", line 136, in <module>
    shortcut = shortcut_handler(line)
  File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 864, in shortcut_handler
    ret = factory(shortcut)
  File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 469, in shortcut_handler
    return PPAShortcutHandler(shortcut)
  File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 426, in __init__
    info = get_ppa_info(self.shortcut)
  File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 380, in get_ppa_info
    ret = get_ppa_info_from_lp(user, ppa)
  File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 110, in get_ppa_info_from_lp
    return get_info_from_lp(lp_url)
  File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 104, in get_info_from_lp
    return get_info_from_https(lp_url, True)
  File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 96, in get_info_from_https
    data = func(lp_url=url, accept_json=accept_json, retry_delays=retry_delays)
  File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 139, in _get_https_content_py3
    cafile=LAUNCHPAD_PPA_CERT)
  File "/usr/lib/python3.7/urllib/request.py", line 222, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/lib/python3.7/urllib/request.py", line 525, in open
    response = self._open(req, data)
  File "/usr/lib/python3.7/urllib/request.py", line 543, in _open
    '_open', req)
  File "/usr/lib/python3.7/urllib/request.py", line 503, in _call_chain
    result = func(*args)
  File "/usr/lib/python3.7/urllib/request.py", line 1360, in https_open
    context=self._context, check_hostname=self._check_hostname)
  File "/usr/lib/python3.7/urllib/request.py", line 1317, in do_open
    encode_chunked=req.has_header('Transfer-encoding'))
  File "/usr/lib/python3.7/http/client.py", line 1229, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/usr/lib/python3.7/http/client.py", line 1275, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/usr/lib/python3.7/http/client.py", line 1224, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/usr/lib/python3.7/http/client.py", line 1016, in _send_output
    self.send(msg)
  File "/usr/lib/python3.7/http/client.py", line 956, in send
    self.connect()
  File "/usr/lib/python3.7/http/client.py", line 1384, in connect
    super().connect()
  File "/usr/lib/python3.7/http/client.py", line 928, in connect
    (self.host,self.port), self.timeout, self.source_address)
  File "/usr/lib/python3.7/socket.py", line 716, in create_connection
    sock.connect(sa)
KeyboardInterrupt

Есть идеи, что может быть причиной этого? Спасибо.