upgrader failes -Could not calculate the upgrade

[dvatsal]

An uresolvable problem occurred while calculating the upgrade

This was likely caused by:
*Unofficial software packages not provided by Ubuntu
Please use the tool 'ppa-purge from the ppa-purge
package to remove software from a LaunchpadPPA and try the upfrade again.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.37 [origin: unknown]
ProcVersionSignature: Ubuntu 4.15.0-118.119-generic 4.15.18
Uname: Linux 4.15.0-118-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.16
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Thu Oct 1 11:33:09 2020
InstallationDate: Installed on 2019-07-08 (450 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2020-10-01 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

It seems that you are running Ubuntu 18.04 on your system but your /etc/apt/sources.list file only has entries for Ubuntu 16.04 (xenial). You'll need to replace xenial with bionic in your sources.list file, ensure your system is up to date, and then try the release upgrade again.

[dvatsal (vatsaldin)]

These are the entries in sources.list file.I replaced Xenial with bionic and tried again.

(base) vatsal@vatsal-XPS-15-9570:~$ cat /etc/apt/sources.list
# deb http://archive.ubuntu.com/ubuntu bionic main restricted universe multiverse
# deb-src http://archive.ubuntu.com/ubuntu bionic main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu bionic-updates main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu bionic-updates main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu bionic-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu bionic-backports main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu bionic-security main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu bionic-security main restricted universe multiverse
# deb http://archive.ubuntu.com/ubuntu bionic-proposed restricted main universe multiverse
# deb-src http://archive.ubuntu.com/ubuntu bionic-proposed restricted main universe multiverse
deb http://archive.canonical.com/ubuntu bionic partner
deb-src http://archive.canonical.com/ubuntu bionic partner

[dvatsal (vatsaldin)]

Received error message as shown in the attachment and same was there originally before changing sources.list file and trying to upgrade.And also note that I use the command to perform upgrade:-

sudo do-release-upgrade -d -f DistUpgradeViewGtk3

[dvatsal (vatsaldin)]

Please also refer this latest screenshot

Where it asks to get all latest updates and than there is no update available and it does not proceed further with upgade as well.

[Launchpad Janitor (janitor)]

[Expired for ubuntu-release-upgrader (Ubuntu) because there has been no activity for 60 days.]