upgrade to ubuntu-18.04: 'ubuntu-minimal' not found

[Pol Vangheluwe]

I tried several times to upgrade to 18.04, but always get the same error: 'essential package ubuntu-minimal not found'.

When I try to install ubuntu-minimal, then I get 'is already the newest version (1.361.1)' - translating from Dutch

When I do a 'locate ubuntu-minimal' then I get this:
/usr/share/doc/ubuntu-minimal
/usr/share/doc/ubuntu-minimal/changelog.gz
/usr/share/doc/ubuntu-minimal/copyright
/var/lib/dpkg/info/ubuntu-minimal.list
/var/lib/dpkg/info/ubuntu-minimal.md5sums

So far, I never had a problem with an overloaded mirror-server, when doing upgrades or updates.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.25
ProcVersionSignature: Ubuntu 4.4.0-135.161-powerpc64-smp 4.4.140
Uname: Linux 4.4.0-135-powerpc64-smp ppc64
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: powerpc
CrashDB: ubuntu
Date: Sun Sep 30 08:54:31 2018
PackageArchitecture: all
ProcEnviron:
 SHELL=/bin/bash
 PATH=(custom, no user)
 LANG=nl_BE.UTF-8
 LANGUAGE=nl_BE:nl
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to xenial on 2018-09-30 (0 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Damian Icely (damianicely)]

Still affecting me upgrating from 18.04 LTS to 20.04 LTS

After updating your package information, the essential package
'ubuntu-minimal' could not be located. This may be because you have
no official mirrors listed in your software sources, or because of
excessive load on the mirror you are using. See /etc/apt/sources.list
for the current list of configured software sources.
In the case of an overloaded mirror, you may want to try the upgrade
again later.

```
Restoring original system state

Aborting
      g package lists... 4%[[B
*** Collecting problem information

The collected information can be sent to the developers to improve the
application. This might take a few minutes.
Reading package lists... Done
Building dependency tree
Reading state information... Done
```

[Danny (ubuntuthebest)]

Confirmed affecting me upgrating from 18.04.5 LTS to 20.04.1 LTS

[ToXinE (toxine)]

Confirmed for upgrading 18.04.5 LTS to 20.04 LTS

[Brett Johnson (linuxturtle)]

Confirmed also for 16.04->18.04 on multiple machines. Original 16.04 installs were mythbuntu, if that helps.

[Brett Johnson (linuxturtle)]

This bug has been static for many years, has anyone found a workaround or fix?

[Brett Johnson (linuxturtle)]

I resolved this problem by modifying my /etc/apt/sources.list to remove the mirror method, and point directly to ubuntu sources. I.e. my old sources.list contained lines like this:

  deb mirror://mirrors.ubuntu.com/mirrors.txt xenial main restricted

Which I modified to this:

  deb http://us.archive.ubuntu.com/ubuntu/ xenial main restricted

[Pol Vangheluwe (linuxonmac)]

My architecture is "powerpc" (Apple G3 - G4 and G5 machines are big-endian machines). Xenial supports both "powerpc" and "ppc64el" but Bionic only supports "ppc64el" (little-endian). So, I am afraid that there is no solution for my problem: Xenial is the last Ubuntu release with support for "powerpc".
Of course, the release-upgrade app should be clearer about this:
- it should not propose an upgrade to a not-supported release;
- it should return a clearer error description when the upgrade fails.