[Bug 1566615] [NEW] unable to upgrade to 16.04 - could not calculate changes

[Rained23]

Public bug reported:

I wanted to update to 16.04,  its give error with "Could not calculate
changes.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: ubuntu-release-upgrader-core 1:15.10.14.4
ProcVersionSignature: Ubuntu 4.2.0-35.40-generic 4.2.8-ckt5
Uname: Linux 4.2.0-35-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Wed Apr  6 10:22:12 2016
InstallationDate: Installed on 2016-03-21 (16 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to wily on 2016-04-06 (0 days ago)
VarLogDistupgradeTermlog:

** Affects: ubuntu-release-upgrader (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug dist-upgrade third-party-packages wily

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https://bugs.launchpad.net/bugs/1566615

Title:
  unable to upgrade to 16.04 - could not calculate changes

Status in ubuntu-release-upgrader package in Ubuntu:
  New

Bug description:
  I wanted to update to 16.04,  its give error with "Could not calculate
  changes.

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: ubuntu-release-upgrader-core 1:15.10.14.4
  ProcVersionSignature: Ubuntu 4.2.0-35.40-generic 4.2.8-ckt5
  Uname: Linux 4.2.0-35-generic x86_64
  ApportVersion: 2.19.1-0ubuntu5
  Architecture: amd64
  CrashDB: ubuntu
  CurrentDesktop: Unity
  Date: Wed Apr  6 10:22:12 2016
  InstallationDate: Installed on 2016-03-21 (16 days ago)
  InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
  PackageArchitecture: all
  SourcePackage: ubuntu-release-upgrader
  UpgradeStatus: Upgraded to wily on 2016-04-06 (0 days ago)
  VarLogDistupgradeTermlog:

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