Cannot upgrade from 18.04 to 20.04 "An unresolvable problem occured while calculating the upgrade."

[Jochen Ehnes]

Description: Ubuntu 18.04.5 LTS
Release: 18.04

I clicked the button to upgrade the system in the dialogue box that popped up telling me that there is a new version of the OS I can upgrade to.

After the Distribution upgrade was running for a short while, it showed the following error message:

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'.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.42
ProcVersionSignature: Ubuntu 5.4.0-62.70~18.04.1-generic 5.4.78
Uname: Linux 5.4.0-62-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.21
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Mon Apr 19 10:28:34 2021
InstallationDate: Installed on 2019-09-17 (579 days ago)
InstallationMedia: Ubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2021-04-19 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

Thanks for taking the time to report this upgrade failure. There is currently a new version of the release upgrader available in -proposed which may resolve the error you've encountered. Please run the following command to test the new version of the upgrader:

  do-release-upgrade -p

Please lets us know the results in this bug report. Thanks again and good luck!

[Jochen Ehnes (jehnes)]

Thanks for the help Brian, really appreciated.

This is just to inform you that it will take a while until I can try this and report the results back to you. This machine is located at my workplace, but due to the recent increase of Covid-19 cases in Singapore we are supposed to work from home for now. As doing a release upgrade is discouraged via ssh, this will have to wait a few weeks until we can go back to the office.

Best regards,
Jochen

[Brian Murray (brian-murray)]

The error that you encountered was with calculating the upgrade, which only changes your /etc/apt/sources.list file from your old release to the new one and then calculates the upgrade. To test the fix it would be enough to just run the upgrade process to the point where it asks you if you want to upgrade and then quit the process. That being said I've enough positive feedback so far to feel confident that the change works so do whatever you feel comfortable with.

[Jochen Ehnes (jehnes)]

Are you talking about this question (see copy of the output in the terminal below)?

Reading cache

Checking package manager

Continue running under SSH?

This session appears to be running under ssh. It is not recommended
to perform a upgrade over ssh currently because in case of failure it
is harder to recover.

If you continue, an additional ssh daemon will be started at port
'1022'.
Do you want to continue?

Continue [yN]

At this time I press N to stop.

However, this comes very early in my experience and the result is the same with and without the -p option. Last time I tried to upgrade the machine directly I also remember more stuff coming out in the terminal before the error occured.

Or is there another point later at which you can choose to upgrade or abort?

[Brian Murray (brian-murray)]

The dialog which follows is the final question before the upgrade actually begins. If you choose N here your system will be restored to its previous state.

Calculating the changes

Do you want to start the upgrade?

3 installed packages are no longer supported by Canonical. You can
still get support from the community.

16 packages are going to be removed. 322 new packages are going to be
installed. 1391 packages are going to be upgraded.

You have to download a total of 1,156 M. This download will take
about 2 minutes with your connection.

Installing the upgrade can take several hours. Once the download has
finished, the process cannot be canceled.

 Continue [yN] Details [d]

[Jochen Ehnes (jehnes)]

Hi Brian,

I just tried it, but it seems to have the same issue:

admin@jv:/home/jochen$ do-release-upgrade -p
Checking for a new Ubuntu release
Get:1 Upgrade tool signature [1,554 B]
Get:2 Upgrade tool [1,349 kB]
Fetched 1,350 kB in 0s (0 B/s)
authenticate 'focal.tar.gz' against 'focal.tar.gz.gpg'
extracting 'focal.tar.gz'
[sudo] password for admin:

To continue please press [ENTER]

Get:1 http://archive.ubuntu.com/ubuntu focal InRelease [265 kB]
Get:2 http://archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
Get:3 http://archive.ubuntu.com/ubuntu focal-backports InRelease [101 kB]
Get:4 http://archive.ubuntu.com/ubuntu focal-security InRelease [114 kB]
Get:5 http://archive.ubuntu.com/ubuntu focal/main i386 Packages [718 kB]
Get:6 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages [970 kB]
Get:7 http://archive.ubuntu.com/ubuntu focal/main Translation-en [506 kB]
Get:8 http://archive.ubuntu.com/ubuntu focal/main amd64 DEP-11 Metadata [494 kB]
Get:9 http://archive.ubuntu.com/ubuntu focal/main DEP-11 48x48 Icons [98.4 kB]
Get:10 http://archive.ubuntu.com/ubuntu focal/main DEP-11 64x64 Icons [163 kB]
Get:11 http://archive.ubuntu.com/ubuntu focal/main amd64 c-n-f Metadata [29.5 kB]
Get:12 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages [8,628 kB]
Get:13 http://archive.ubuntu.com/ubuntu focal/universe i386 Packages [4,642 kB]
Get:14 http://archive.ubuntu.com/ubuntu focal/universe Translation-en [5,124 kB]
Get:15 http://archive.ubuntu.com/ubuntu focal/universe amd64 DEP-11 Metadata [3,603 kB]
Get:16 http://archive.ubuntu.com/ubuntu focal/universe DEP-11 48x48 Icons [3,016 kB]
Get:17 http://archive.ubuntu.com/ubuntu focal/universe DEP-11 64x64 Icons [7,794 kB]
Get:18 http://archive.ubuntu.com/ubuntu focal/universe amd64 c-n-f Metadata [265 kB]
Get:19 http://archive.ubuntu.com/ubuntu focal-updates/main i386 Packages [480 kB]
Get:20 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages [988 kB]
Get:21 http://archive.ubuntu.com/ubuntu focal-updates/main Translation-en [224 kB]
Get:22 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 DEP-11 Metadata [264 kB]
Get:23 http://archive.ubuntu.com/ubuntu focal-updates/main DEP-11 48x48 Icons [55.6 kB]
Get:24 http://archive.ubuntu.com/ubuntu focal-updates/main DEP-11 64x64 Icons [87.9 kB]
Get:25 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 c-n-f Metadata [13.4 kB]
Get:26 http://archive.ubuntu.com/ubuntu focal-updates/universe amd64 Packages [777 kB]
Get:27 http://archive.ubuntu.com/ubuntu focal-updates/universe i386 Packages [574 kB]
Get:28 http://archive.ubuntu.com/ubuntu focal-updates/universe Translation-en [167 kB]
Get:29 http://archive.ubuntu.com/ubuntu focal-updates/universe amd64 DEP-11 Metadata [323 kB]
Get:30 http://archive.ubuntu.com/ubuntu focal-updates/universe DEP-11 48x4...

[Launchpad Janitor (janitor)]

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