[Bug 1773663] [NEW] I cannot upgrade from ubuntu 16.04 to 18.04

[Bongjoo Seo]

Public bug reported:

When I upgrade ubuntu 18.04, "could not calculate the upgrade" message
popup

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.25
ProcVersionSignature: Ubuntu 4.4.0-127.153-generic 4.4.128
Uname: Linux 4.4.0-127-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.17
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Mon May 28 00:06:07 2018
InstallationDate: Installed on 2016-09-26 (608 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to xenial on 2018-05-27 (0 days ago)
VarLogDistupgradeTermlog:

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


** Tags: amd64 apport-bug dist-upgrade xenial

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https://bugs.launchpad.net/bugs/1773663

Title:
  I cannot upgrade from ubuntu 16.04 to 18.04

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

Bug description:
  When I upgrade ubuntu 18.04, "could not calculate the upgrade" message
  popup

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: ubuntu-release-upgrader-core 1:16.04.25
  ProcVersionSignature: Ubuntu 4.4.0-127.153-generic 4.4.128
  Uname: Linux 4.4.0-127-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2.17
  Architecture: amd64
  CrashDB: ubuntu
  CurrentDesktop: Unity
  Date: Mon May 28 00:06:07 2018
  InstallationDate: Installed on 2016-09-26 (608 days ago)
  InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
  PackageArchitecture: all
  SourcePackage: ubuntu-release-upgrader
  UpgradeStatus: Upgraded to xenial on 2018-05-27 (0 days ago)
  VarLogDistupgradeTermlog:

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