IKEA Tradfri integration cannot be re-added after upgrade to 0.113.3

I’ve just upgraded to the latest version ( 0.113.3 from 0.108) and removed and added back in the Ikea Tradfri integration through the UI. However, when entering the Security code I get: Unknown error occurred.

The log shows:

2020-08-06 20:37:24 ERROR (MainThread) [aiohttp.server] Error handling request
Traceback (most recent call last):
  File "/Users/david/homeassistant/lib/python3.8/site-packages/aiohttp/web_protocol.py", line 418, in start
    resp = await task
  File "/Users/david/homeassistant/lib/python3.8/site-packages/aiohttp/web_app.py", line 458, in _handle
    resp = await handler(request)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/aiohttp/web_middlewares.py", line 119, in impl
    return await handler(request)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/components/http/real_ip.py", line 39, in real_ip_middleware
    return await handler(request)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/components/http/ban.py", line 73, in ban_middleware
    return await handler(request)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/components/http/auth.py", line 127, in auth_middleware
    return await handler(request)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/components/http/view.py", line 129, in handle
    result = await result
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/components/config/config_entries.py", line 145, in post
    return await super().post(request, flow_id)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/components/http/data_validator.py", line 60, in wrapper
    result = await method(view, request, *args, **kwargs)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/helpers/data_entry_flow.py", line 106, in post
    result = await self._flow_mgr.async_configure(flow_id, data)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/data_entry_flow.py", line 153, in async_configure
    result = await self._async_handle_step(flow, cur_step["step_id"], user_input)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/data_entry_flow.py", line 201, in _async_handle_step
    result: Dict = await getattr(flow, method)(user_input)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/components/tradfri/config_flow.py", line 53, in async_step_auth
    auth = await authenticate(
  File "/Users/david/homeassistant/lib/python3.8/site-packages/homeassistant/components/tradfri/config_flow.py", line 168, in authenticate
    key = await api_factory.generate_psk(security_code)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/pytradfri/api/aiocoap_api.py", line 195, in generate_psk
    self._psk = await self.request(command)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/pytradfri/api/aiocoap_api.py", line 155, in request
    result = await self._execute(api_commands)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/pytradfri/api/aiocoap_api.py", line 146, in _execute
    _, res = await self._get_response(msg)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/pytradfri/api/aiocoap_api.py", line 95, in _get_response
    r = await pr.response
  File "/Users/david/homeassistant/lib/python3.8/site-packages/aiocoap/protocol.py", line 816, in _run_outer
    yield from cls._run(app_request, response, weak_observation, protocol, log, exchange_monitor_factory)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/aiocoap/protocol.py", line 865, in _run
    blockresponse = yield from blockrequest.response
  File "/Users/david/homeassistant/lib/python3.8/site-packages/aiocoap/protocol.py", line 695, in _init_phase2
    yield from self.protocol.fill_remote(self.app_request)
  File "/Users/david/homeassistant/lib/python3.8/site-packages/aiocoap/protocol.py", line 426, in fill_remote
    raise RuntimeError("No transport could route message")
RuntimeError: No transport could route message

Im running on mac, using python venv.
I had Tradfri working fine before the upgrade, and had removed and re-added the integration multiple times before without issue (you have to every time IKEA make an update)
I have pytradfri-6.4.0 installed.
autoconf 2.69 is already installed and up-to-date

Google/forum search hasn’t helped find me an answer. I’d like to avoid a complete delete of the venv dir and .homeassistant dir and starting afresh.

Can anyone help please?
Thanks

FWIW, I just had to start again to get this working. New venv, new home assistant install, copied over the yaml, fixed the inevitable issues…