E:

Failed to fetch http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu/dists/focal/InRelease  403  Forbidden [IP: 91.189.95.83 80]

E:

The repository
'
http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu focal InRelease
'
is not signed.

N:

Updating from such a repository can
'
t be done securely, and is therefore disabled by default.

N:

See apt-secure(8) manpage for repository creation and user configuration details.

E:

Problem executing scripts APT::Update::Post-Invoke-Success
'
if /usr/bin/test -w /var/lib/command-not-found/ -a -e /usr/lib/cnf-update-db; then /usr/lib/cnf-update-db
>
/dev/null; fi
'

E:

Sub-process returned an error code