Upgrade from 14.04. to 15.04. fails. It sais: could not determine, which acualisations are available

[Stefan Levedag]

It sais, an unsolvable problem has occurred.

In a second try i switched off any unofficial software from being upgraded but the error remains.

Kind regards,

SL

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.8
ProcVersionSignature: Ubuntu 3.13.0-70.113-generic 3.13.11-ckt29
Uname: Linux 3.13.0-70-generic i686
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: i386
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Tue Dec 1 15:05:12 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2012-03-02 (1369 days ago)
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2015-12-01 (0 days ago)
VarLogDistupgradeTermlog:

mtime.conffile..etc.update.manager.release.upgrades: 2015-12-01T14:45:19.898620