not able to upgrade linux neither i am able to install google chrome inspite of trying to install it multiple times

[Aayushi SIngh]

Tried upgrading my linux from version 16 to 18 to which it showed the below error:

An unresolvable 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 Launchpad PPA and
try the upgrade again.

i have also tried installing google chrome and honestly everything seemed normal while installing and after i complete the installation process i would see that google chrome still hasn't been installed. When i tried opening the google chrome package again it showed 'install' bar instead of 'remove' bar. I have tried installing google chrome through terminal but to no avail it has helped.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.30
ProcVersionSignature: Ubuntu 4.4.0-189.219-generic 4.4.232
Uname: Linux 4.4.0-189-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.24
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Mon Sep 7 15:38:50 2020
InstallationDate: Installed on 2019-11-16 (295 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to xenial on 2020-09-07 (0 days ago)
VarLogDistupgradeTermlog: