erreur a la mise ajour de ubuntu 15.04 -

[Renard henri]

j'utilisais 14.10 sans probleme. A l'invitation de mise a jour de 15.04, un probleme de réseaux a tout bloqué.Aai tenté de remettre le liveCD 12.03. que j'avais gardé: problème !
Merci de me dépanner!

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.10.29
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic x86_64
ApportVersion: 2.0.1-0ubuntu5
Architecture: amd64
CasperVersion: 1.315
Date: Mon May 4 11:14:29 2015
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- debian-installer/language=fr keyboard-configuration/layoutcode?=fr keyboard-configuration/variantcode?=oss maybe-ubiquity
LiveMediaBuild: Ubuntu 12.04 "Precise" - Build amd64 LIVE Binary 20120425-15:28
ProcEnviron:
 LANGUAGE=fr_FR.UTF-8
 TERM=linux
 PATH=(custom, no user)
 LANG=fr_FR.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Ubuntu Foundations Team Bug Bot (crichton)]

Exception during installation:
May 4 09:13:55 ubuntu plugininstall.py: Traceback (most recent call last):
May 4 09:13:55 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 1730, in <module>
May 4 09:13:55 ubuntu plugininstall.py: install.run()
May 4 09:13:55 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 55, in wrapper
May 4 09:13:55 ubuntu plugininstall.py: func(self)
May 4 09:13:55 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 174, in run
May 4 09:13:55 ubuntu plugininstall.py: self.install_language_packs()
May 4 09:13:55 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 664, in install_language_packs
May 4 09:13:55 ubuntu plugininstall.py: self.do_install(self.langpacks, langpacks=True)
May 4 09:13:55 ubuntu plugininstall.py: File "/usr/lib/ubiquity/ubiquity/install_misc.py", line 856, in do_install
May 4 09:13:55 ubuntu plugininstall.py: with Cache() as cache:
May 4 09:13:55 ubuntu plugininstall.py: AttributeError: __exit__
May 4 09:13:55 ubuntu plugininstall.py:

[Marcus Tomlinson (marcustomlinson)]

This release of Ubuntu is no longer receiving maintenance updates. If this is still an issue on a maintained version of Ubuntu please let us know.

[Launchpad Janitor (janitor)]

[Expired for ubiquity (Ubuntu) because there has been no activity for 60 days.]