Problem found. the package 'six' was installed both by pip3 and by apt.
The pip3 version in /usr/local/lib/python3.8/dist-packages/six.py was at
version 1.11.0, whereas the Ubuntu version is at 1.14.0
Removing the old version fixed the problem.
** Changed in: python-certbot (Ubuntu)
In this function:
_normalize_host(host, scheme):
return six.ensure_str(
b".".join([_idna_encode(label) for label in host.split(".")])
)
The parameter passed is b'acme-v02.api.letsencrypt.org', but
six.ensure_str() throws an exception with that parameter.
In six.ensure_str, I imagine this is
Thank you for taking the time to report this bug and helping to make
Ubuntu better.
One other person reported this issue in Debian, but nobody managed to
reproduce it. Details, and request for further details from an affected
user at: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=951696
**
