Could not calculate the upgrade

[priyanka]

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.

If none of this applies, then please report this bug using the command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal. If you want to investigate this yourself the log files in '/var/log/dist-upgrade' will contain details about the upgrade. Specifically, look at 'main.log' and 'apt.log'.

ProblemType: Bug
DistroRelease: Ubuntu 23.04
Package: ubuntu-release-upgrader-core 1:23.04.7
ProcVersionSignature: Ubuntu 6.2.0-37.38-generic 6.2.16
Uname: Linux 6.2.0-37-generic x86_64
ApportVersion: 2.26.1-0ubuntu2.1
Architecture: amd64
CasperMD5CheckResult: unknown
CrashDB: ubuntu
CrashReports:
 644:1000:125:0:2023-11-24 16:22:46.474689239 +0530:2023-11-24 16:22:46.474689239 +0530:/var/crash/_usr_bin_gnome-control-center.1000.upload
 640:1000:125:2822093:2023-11-24 16:22:46.474689239 +0530:2023-11-24 16:22:46.510689239 +0530:/var/crash/_usr_bin_gnome-control-center.1000.crash
 600:120:125:37:2023-11-24 14:01:27.702767081 +0530:2023-11-24 14:01:27.702767081 +0530:/var/crash/_usr_bin_gnome-control-center.1000.uploaded
CurrentDesktop: ubuntu:GNOME
Date: Fri Nov 24 14:52:37 2023
InstallationDate: Installed on 2022-12-31 (327 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to lunar on 2023-11-24 (0 days ago)
VarLogDistupgradeTermlog: