aborting without informative error message

[Nico Schlömer]

I'm trying to upgrade from 19.10 to 20.04 (devel). Unfortunately, the do-release-upgrade process aborts after "Calculating the changes" without saying why:
```
sudo do-release-upgrade -d
```
```
Checking for a new Ubuntu release
Get:1 Upgrade tool signature [1,554 B]
Get:2 Upgrade tool [1,334 kB]
Fetched 1,335 kB in 0s (0 B/s)
authenticate 'focal.tar.gz' against 'focal.tar.gz.gpg'
extracting 'focal.tar.gz'

Reading cache

Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Hit http://de.archive.ubuntu.com/ubuntu eoan InRelease
Hit http://de.archive.ubuntu.com/ubuntu eoan-updates InRelease
Ign http://dl.google.com/linux/chrome/deb stable InRelease
Hit http://ppa.launchpad.net/nschloe/inkscape-backports/ubuntu eoan InRelease
Hit http://de.archive.ubuntu.com/ubuntu eoan-backports InRelease
Hit http://dl.google.com/linux/chrome/deb stable Release
Hit http://ppa.launchpad.net/nschloe/mmg-test/ubuntu eoan InRelease
Hit http://ppa.launchpad.net/nschloe/trilinos-backports/ubuntu eoan InRelease
Ign https://dl.bintray.com/etcher/debian stable InRelease
Get:1 https://dl.bintray.com/etcher/debian stable Release [3,674 B]
Fetched 3,674 B in 0s (0 B/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done

Updating repository information

Third party sources disabled

Some third party entries in your sources.list were disabled. You can
re-enable them after the upgrade with the 'software-properties' tool
or your package manager.

To continue please press [ENTER]

Hit http://de.archive.ubuntu.com/ubuntu eoan InRelease
Hit http://de.archive.ubuntu.com/ubuntu eoan-updates InRelease
Hit http://de.archive.ubuntu.com/ubuntu eoan-backports InRelease
Fetched 0 B in 0s (0 B/s)

Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done

Calculating the changes

Calculating the changes

Restoring original system state

Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
```

[Chippo Elder (chiphog)]

This seems like the same bug as
<https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1849669>

[Chippo Elder (chiphog)]

Oh no! I posted the above comment into the wrong thread. I can't seem to delete it. Sorry.