not possible to upgrade to ubuntu 20.04

[gianluca]

not sure what to report, not much information, during the do-release-upgrade

--------------
Calculating the changes

Calculating the changes

Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade.

If none of this applies, then please report this bug using the
command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal. If
you want to investigate this yourself the log files in
'/var/log/dist-upgrade' will contain details about the upgrade.
Specifically, look at 'main.log' and 'apt.log'.
--------------

and that's all.

best,
g.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.41
ProcVersionSignature: Ubuntu 4.15.0-126.129-generic 4.15.18
Uname: Linux 4.15.0-126-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.20
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Fri Dec 11 15:02:02 2020
InstallationDate: Installed on 2016-12-15 (1457 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2020-12-11 (0 days ago)