error: module 'acme. challenges' has no attribute 'TLSSNI01'

[Philipp Dreimann]

After upgrading to ubuntu 20.04 certbot fails to create new certificates:

$ certbot renew --dry-run

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/certbot/renewal.py", line 449, in handle_renewal_request
    main.renew_cert(lineage_config, plugins, renewal_candidate)
  File "/usr/lib/python3/dist-packages/certbot/main.py", line 1208, in renew_cert
    renewed_lineage = _get_and_save_cert(le_client, config, lineage=lineage)
  File "/usr/lib/python3/dist-packages/certbot/main.py", line 116, in _get_and_save_cert
    renewal.renew_cert(config, domains, le_client, lineage)
  File "/usr/lib/python3/dist-packages/certbot/renewal.py", line 307, in renew_cert
    new_cert, new_chain, new_key, _ = le_client.obtain_certificate(domains, new_key)
  File "/usr/lib/python3/dist-packages/certbot/client.py", line 348, in obtain_certificate
    orderr = self._get_order_and_authorizations(csr.data, self.config.allow_subset_of_names)
  File "/usr/lib/python3/dist-packages/certbot/client.py", line 396, in _get_order_and_authorizations
    authzr = self.auth_handler.handle_authorizations(orderr, best_effort)
  File "/usr/lib/python3/dist-packages/certbot/auth_handler.py", line 62, in handle_authorizations
    achalls = self._choose_challenges(authzrs)
  File "/usr/lib/python3/dist-packages/certbot/auth_handler.py", line 206, in _choose_challenges
    self._get_chall_pref(authzr.body.identifier.value),
  File "/usr/lib/python3/dist-packages/certbot/auth_handler.py", line 221, in _get_chall_pref
    plugin_pref = self.auth.get_chall_pref(domain)
  File "/usr/lib/python3/dist-packages/certbot_nginx/configurator.py", line 1110, in get_chall_pref
    return [challenges.HTTP01, challenges.TLSSNI01]
AttributeError: module 'acme.challenges' has no attribute 'TLSSNI01'

/etc/letsencrypt/renewal/host.conf:
# renew_before_expiry = 30 days
version = 0.36.0
archive_dir = /etc/letsencrypt/archive/host
cert = /etc/letsencrypt/live/host/cert.pem
privkey = /etc/letsencrypt/live/host/privkey.pem
chain = /etc/letsencrypt/live/host/chain.pem
fullchain = /etc/letsencrypt/live/host/fullchain.pem

# Options used in the renewal process
[renewalparams]
account = abcdef1234567890
authenticator = nginx
installer = nginx
server = https://acme-v02.api.letsencrypt.org/directory

$ dpkg -l|grep certbot
ii certbot 0.40.0-1 all automatically configure HTTPS using Let's Encrypt
ii python3-certbot 0.40.0-1 all main library for certbot
ii python3-certbot-nginx 0.39.0-1 all Nginx plugin for Certbot

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.