The upgrade from trusty to xenial doesn't run well

[Benoit THIBAUD]

First test :
1-updated my old install of trusty
2-reboot
3-autoremove
4-update-manager -d -c in a terminal
5-reboot
6-update-manager -d -c in a terminal again
7-clic on the button "mise à niveau"
8-message "erreur -> authentification de certains paquets : module-init-tools"

Second test :
1-install a new trusty in that partition
2-made all the update
3-after all the reboot : update-manager -d -c in a terminal
4-new reboot
5-update-manager -d -c in a terminal again
6-clic on the button "mise à niveau"
7-message "impossible d'évaluer la mise à niveau" you have to advertise this bug with the command "ubuntu-bug ubuntu-release-upgrader-core" in a terminal

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.8
ProcVersionSignature: Ubuntu 3.19.0-51.58~14.04.1-generic 3.19.8-ckt13
Uname: Linux 3.19.0-51-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: XFCE
Date: Sun Feb 28 17:06:13 2016
InstallationDate: Installed on 2016-02-28 (0 days ago)
InstallationMedia: Xubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2016-02-28 (0 days ago)
VarLogDistupgradeTermlog:

[Launchpad Janitor (janitor)]

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