upgrade from 15.10 to 16.04 failed on a PowerBook G4, ppc

[ernsteiswuerfel]

W:Fehlschlag beim Holen von http://ports.ubuntu.com/ubuntu-ports/dists/xenial/InRelease Erwarteter Eintrag »partner/binary-powerpc/Packages« konnte in Release-Datei nicht gefunden werden (falscher Eintrag in sources.list oder missgebildete Datei).
, E:Einige Indexdateien konnten nicht heruntergeladen werden. Sie wurden ignoriert oder alte an ihrer Stelle benutzt.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: ubuntu-release-upgrader-core 1:15.10.14.4
ProcVersionSignature: Ubuntu 4.2.0-35.40-powerpc-smp 4.2.8-ckt5
Uname: Linux 4.2.0-35-powerpc-smp ppc
ApportVersion: 2.19.1-0ubuntu5
Architecture: powerpc
CrashDB: ubuntu
Date: Sun Apr 17 16:15:41 2016
InstallationDate: Installed on 2015-09-16 (213 days ago)
InstallationMedia: Ubuntu-MATE 15.10 "Wily Werewolf" - Alpha powerpc (20150827)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=de_AT:de
 TERM=xterm
 PATH=(custom, no user)
 LANG=de_AT.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
Symptom: ubuntu-release-upgrader
UpgradeStatus: Upgraded to wily on 2016-04-17 (0 days ago)
VarLogDistupgradeAptlog:
 Log time: 2016-04-17 15:57:35.318715
 Log time: 2016-04-17 15:57:54.036725
VarLogDistupgradeTermlog:

[Launchpad Janitor (janitor)]

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

[wwp (subscript-4)]

I get the exact same error while attempting to upgrade a macmini powerpc (g4) from ubuntu mate 15.04 to 15.10.

[wwp (subscript-4)]

BTW, I could get rid of the error and proceed to installation by restricting the list of repositories to the Canonical ones only (i.e. disabling the extra Canonical-partners one) in software-properties-gtk.

[ernsteiswuerfel (erhard-f)]

Thanks for the hint wwp! Did as you suggested and now the update to 16.04 is working too.