root@test-impish-1968067:~# lsb_release -c
Codename:       impish
root@test-impish-1968067:~# apt policy ubuntu-advantage-tools
ubuntu-advantage-tools:
  Installed: 27.7~21.10.1
  Candidate: 27.7~21.10.1
  Version table:
 *** 27.7~21.10.1 500
        500 http://archive.ubuntu.com/ubuntu impish-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     27.2.2~21.10.1 500
        500 http://archive.ubuntu.com/ubuntu impish/main amd64 Packages
root@test-impish-1968067:~#  ua attach REDACTED
This machine is now attached to 'server-team-ua-client-ci-uaa'

SERVICE       ENTITLED  STATUS    DESCRIPTION
cc-eal        yes       n/a       Common Criteria EAL2 Provisioning Packages
cis           yes       n/a       Security compliance and audit tools
esm-infra     yes       n/a       UA Infra: Extended Security Maintenance (ESM)
fips          yes       n/a       NIST-certified core packages
fips-updates  yes       n/a       NIST-certified core packages with priority security updates
livepatch     yes       n/a       Canonical Livepatch service

NOTICES
Operation in progress: ua attach

Enable services with: ua enable <service>

                Account: UA Client Test
           Subscription: server-team-ua-client-ci-uaa
            Valid until: 9999-12-31 00:00:00+00:00
Technical support level: essential
root@test-impish-1968067:~# sudo python3 /usr/lib/ubuntu-advantage/upgrade_lts_contract.py
Starting upgrade-lts-contract.
Traceback (most recent call last):
  File "/usr/lib/ubuntu-advantage/upgrade_lts_contract.py", line 99, in <module>
    process_contract_delta_after_apt_lock()
  File "/usr/lib/ubuntu-advantage/upgrade_lts_contract.py", line 61, in process_contract_delta_after_apt_lock
    current_release = version_to_codename[current_version]
KeyError: '21.10'
root@test-impish-1968067:~# cat <<EOF >/etc/apt/sources.list.d/ubuntu-$(lsb_release -cs)-proposed.list
# Enable Ubuntu proposed archive
deb http://archive.ubuntu.com/ubuntu/ $(lsb_release -cs)-proposed restricted main multiverse universe
EOF
root@test-impish-1968067:~# apt update
Hit:1 http://security.ubuntu.com/ubuntu impish-security InRelease
Hit:2 http://archive.ubuntu.com/ubuntu impish InRelease
Hit:3 http://archive.ubuntu.com/ubuntu impish-updates InRelease
Hit:4 http://archive.ubuntu.com/ubuntu impish-backports InRelease
Get:5 http://archive.ubuntu.com/ubuntu impish-proposed InRelease [270 kB]
Get:6 http://archive.ubuntu.com/ubuntu impish-proposed/restricted amd64 Packages [147 kB]
Get:7 http://archive.ubuntu.com/ubuntu impish-proposed/restricted Translation-en [21.1 kB]
Get:8 http://archive.ubuntu.com/ubuntu impish-proposed/restricted amd64 c-n-f Metadata [116 B]
Get:9 http://archive.ubuntu.com/ubuntu impish-proposed/main amd64 Packages [144 kB]
Get:10 http://archive.ubuntu.com/ubuntu impish-proposed/main Translation-en [33.1 kB]
Get:11 http://archive.ubuntu.com/ubuntu impish-proposed/main amd64 c-n-f Metadata [2068 B]
Get:12 http://archive.ubuntu.com/ubuntu impish-proposed/multiverse Translation-en [3404 B]
Get:13 http://archive.ubuntu.com/ubuntu impish-proposed/multiverse amd64 c-n-f Metadata [116 B]
Get:14 http://archive.ubuntu.com/ubuntu impish-proposed/universe amd64 Packages [33.2 kB]
Get:15 http://archive.ubuntu.com/ubuntu impish-proposed/universe Translation-en [19.0 kB]
Get:16 http://archive.ubuntu.com/ubuntu impish-proposed/universe amd64 c-n-f Metadata [1968 B]
Fetched 675 kB in 1s (1046 kB/s)
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
23 packages can be upgraded. Run 'apt list --upgradable' to see them.
root@test-impish-1968067:~# apt install ubuntu-advantage-tools
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following package was automatically installed and is no longer required:
  libfreetype6
Use 'apt autoremove' to remove it.
The following packages will be upgraded:
  ubuntu-advantage-tools
1 upgraded, 0 newly installed, 0 to remove and 22 not upgraded.
Need to get 867 kB of archives.
After this operation, 15.4 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu impish-proposed/main amd64 ubuntu-advantage-tools amd64 27.8~21.10.1 [867 kB]
Fetched 867 kB in 0s (5966 kB/s)
Preconfiguring packages ...
(Reading database ... 32750 files and directories currently installed.)
Preparing to unpack .../ubuntu-advantage-tools_27.8~21.10.1_amd64.deb ...
Unpacking ubuntu-advantage-tools (27.8~21.10.1) over (27.7~21.10.1) ...
Setting up ubuntu-advantage-tools (27.8~21.10.1) ...
Installing new version of config file /etc/ubuntu-advantage/help_data.yaml ...
Processing triggers for man-db (2.9.4-2) ...
Scanning processes...

No services need to be restarted.

No containers need to be restarted.

No user sessions are running outdated binaries.
root@test-impish-1968067:~# sudo python3 /usr/lib/ubuntu-advantage/upgrade_lts_contract.py
Starting upgrade-lts-contract.
upgrade-lts-contract processing contract deltas: focal -> impish
upgrade-lts-contract succeeded after 0 retries
root@test-impish-1968067:~# echo $?
0