Unable to upgrade to 15.10 from 15.04

[Craig Carnell]

Upgraded system from 14.04 then to 15.04 (it seemed to skip 14/10). I run do-release-upgrade to check for an update and it wont update to 15.10.

I did at one point accidentally do the release upgrade to 16.04 but I stopped it before the first prompt to download anything.

cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=15.04
DISTRIB_CODENAME=vivid
DISTRIB_DESCRIPTION="Ubuntu 15.04"

do-release-upgrade:

Checking for a new Ubuntu release
Get:1 Upgrade tool signature [198 B]
Get:2 Upgrade tool [1,232 kB]
Fetched 1,232 kB in 0s (0 B/s)
authenticate 'wily.tar.gz' against 'wily.tar.gz.gpg'
extracting 'wily.tar.gz'

Reading cache

Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done
Hit http://archive.ubuntu.com vivid InRelease
Hit http://security.ubuntu.com vivid-security InRelease
Hit http://archive.ubuntu.com vivid-updates InRelease
Hit http://security.ubuntu.com vivid-security/main amd64 Packages
Hit http://security.ubuntu.com vivid-security/restricted amd64 Packages
Hit http://security.ubuntu.com vivid-security/main i386 Packages
Hit http://security.ubuntu.com vivid-security/restricted i386 Packages
Hit http://security.ubuntu.com vivid-security/main Translation-en
Hit http://security.ubuntu.com vivid-security/restricted Translation-en
Hit http://archive.ubuntu.com vivid/main amd64 Packages
Hit http://archive.ubuntu.com vivid/restricted amd64 Packages
Hit http://archive.ubuntu.com vivid/main i386 Packages
Hit http://archive.ubuntu.com vivid/restricted i386 Packages
Hit http://archive.ubuntu.com vivid/main Translation-en_GB
Hit http://archive.ubuntu.com vivid/main Translation-en
Hit http://archive.ubuntu.com vivid/restricted Translation-en_GB
Hit http://archive.ubuntu.com vivid/restricted Translation-en
Hit http://archive.ubuntu.com vivid-updates/main amd64 Packages
Hit http://archive.ubuntu.com vivid-updates/restricted amd64 Packages
Hit http://archive.ubuntu.com vivid-updates/main i386 Packages
Hit http://archive.ubuntu.com vivid-updates/restricted i386 Packages
Hit http://archive.ubuntu.com vivid-updates/main Translation-en
Hit http://archive.ubuntu.com vivid-updates/restricted Translation-en
Fetched 0 B in 0s (0 B/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done

Updating repository information
Get:1 http://security.ubuntu.com wily-security InRelease [64.4 kB]
Hit http://archive.ubuntu.com wily InRelease
Get:2 http://security.ubuntu.com wily-security/main amd64 Packages [34.7 kB]
Hit http://archive.ubuntu.com wily-updates InRelease
Get:3 http://security.ubuntu.com wily-security/restricted amd64 Packages [28 B]
Get:4 http://security.ubuntu.com wily-security/main i386 Packages [34.0 kB]
Get:5 http://security.ubuntu.com wily-security/restricted i386 Packages [28 B]
Hit http://security.ubuntu.com wily-security/main Translation-en
Hit http://security.ubuntu.com wily-security/restricted Translation-en
Hit http://archive.ubuntu.com wily/main amd64 Packages
Hit http://archive.ubuntu.com wily/restricted amd64 Packages
Hit http://archive.ubuntu.com wily/main i386 Packages
Hit http://archive.ubuntu.com wily/restricted i386 Packages
Hit http://archive.ubuntu.com wily/main Translation-en_GB
Hit http://archive.ubuntu.com wily/main Translation-en
Hit http://archive.ubuntu.com wily/restricted Translation-en_GB
Hit http://archive.ubuntu.com wily/restricted Translation-en
Hit http://archive.ubuntu.com wily-updates/main amd64 Packages
Hit http://archive.ubuntu.com wily-updates/restricted amd64 Packages
Hit http://archive.ubuntu.com wily-updates/main i386 Packages
Hit http://archive.ubuntu.com wily-updates/restricted i386 Packages
Hit http://archive.ubuntu.com wily-updates/main Translation-en
Hit http://archive.ubuntu.com wily-updates/restricted Translation-en
Fetched 133 kB in 0s (0 B/s)

Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done

Calculating the changes

Calculating the changes

Could not determine the upgrade

An unresolvable problem occurred while calculating the upgrade.

This can be caused by:
* Upgrading to a pre-release version of Ubuntu
* Running the current pre-release version of Ubuntu
* Unofficial software packages not provided by Ubuntu

If none of this applies, then please report this bug using the
command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal.

Restoring original system state

Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: ubuntu-release-upgrader-core 1:15.04.14.3
Uname: Linux 3.13.2-031302-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.7
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Fri Nov 13 15:20:37 2015
InstallationDate: Installed on 2014-01-02 (680 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to vivid on 2015-11-13 (0 days ago)

[Brian Murray (brian-murray)]

From VarLogDistUpgradeMainlogt.txt:

2015-11-13 15:02:38,914 DEBUG Marking 'ubuntu-desktop' for upgrade
2015-11-13 15:02:39,111 WARNING Can't mark 'ubuntu-desktop' for upgrade (E:Unable to correct problems, you have held broken packages.)
2015-11-13 15:02:39,157 DEBUG blacklist expr 'unity$' matches 'unity'
2015-11-13 15:02:39,157 DEBUG The package 'unity' is marked for removal but it's in the removal blacklist
2015-11-13 15:02:39,407 ERROR Dist-upgrade failed: 'The package 'unity' is marked for removal but it is in the removal blacklist.'

[Launchpad Janitor (janitor)]

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