Comment 15 for bug 2049785

I got a Focal ISO and run it in a virtual machine.

Enabled proposed and now upgrading update-manager forces the installation of a newer ubuntu-advantage-tools:

--->
$ sudo apt install update-manager --verbose-versions
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
   python3-update-manager (1:20.04.10.20)
   ubuntu-advantage-tools (31.1~20.04)
   ubuntu-pro-client (31.1~20.04)
   ubuntu-pro-client-l10n (31.1~20.04)
   update-manager-core (1:20.04.10.20)
The following NEW packages will be installed:
   ubuntu-pro-client (31.1~20.04)
   ubuntu-pro-client-l10n (31.1~20.04)
The following packages will be upgraded:
   python3-update-manager (1:20.04.10.11 => 1:20.04.10.20)
   ubuntu-advantage-tools (27.13.6~20.04.1 => 31.1~20.04)
   update-manager (1:20.04.10.11 => 1:20.04.10.20)
   update-manager-core (1:20.04.10.11 => 1:20.04.10.20)
<---

I confirm then that launching and finishing update-manager without internet connection produces no error any more.