Can't install 'xubuntu-core'

[DLCBurggraaff]

Upgrading from Xubuntu 14.04.4 to 16.04 Beta1 using "sudo update-manager -d".

In step 2 "Setting new software channels" I get a popup reading:
-- Can't install 'xubuntu-core'
-- It was impossible to install a required package. Please report this bug ...

After closing this popup the installation continues until at the end of step 3 "Getting new packages" I get another popup reading:
-- Could not download the upgrades
-- The upgrade has aborted. Please ...
-- Failed to fetch http://nl3.archive.ubuntu.com/ubuntu/pool/universe/libs/libsexy/libsexy2_0.1.11-2.1ubuntu1_amd64.deb 403 Forbidden [IP: 109.72.87.236 80]

After closing this popup the installation stops.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.8
ProcVersionSignature: Ubuntu 4.2.0-30.36~14.04.1-generic 4.2.8-ckt3
Uname: Linux 4.2.0-30-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: XFCE
Date: Sat Mar 5 12:30:54 2016
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2016-03-05 (0 days ago)
VarLogDistupgradeTermlog:

[DLCBurggraaff (burdi)]

I forgot to mention that to come this far I created the /etc/update-manager/release-upgrades.d/unauth.cfg as mentioned in #1550022

[DLCBurggraaff (burdi)]

To verify that the "libsexy" problem was still there I restored my pre-upgrade situation and ran "sudo update-manager -d" again: the libsexy problem was still there.

I then restored my pre-upgrade situation once more, in "Software & Updates" changed the Download server from "http://nl3.archive.ubuntu.com/ubuntu" to the "Main server" and ran "sudo update-manager -d" again: step 3 "Getting new packages" took significantly longer but the libsexy problem was gone.

Step 4 "Installing the upgrades" started alright but at about 2/3, shortly after the question whether or not /etc/udev/udev.conf should be replaces the screen went black and the keyboard went dead. When ssh'in from another box top told me that only the "xenial" executable was running. I issued a "powerdown" command to shut the box down while retaining the logs etc.

Let me know what logs (if any) you would like to see.

[DLCBurggraaff (burdi)]

I just happened to read http://xubuntu.org/news/xubuntu-16-04-lts-beta-1/ where is said:

Please note! No upgrade testing was undertaken during this milestone. There are issues currently when upgrading to Xenial Xerus. This release is not suitable for upgrading.

:(

[Brian Murray (brian-murray)]

The issue with libsexy2 seems to be one with your local mirror. Checking the main archive that file is accessible. Could you try switching mirrors and upgrading again?

[DLCBurggraaff (burdi)]

This report was for using 16.04 *Beta1* for upgrading Xubuntu from 14.04.4, which beta, as I found out after reporting, was not suitable for upgrading.
A few days ago I upgraded Xubuntu from 14.04.4 to 16.04.1 successfully.
This issue can be closed.
Thkx. :D