I was unable to upgrade the ubuntu version

[Hriteek Bista]

I disabled the third party PPA and continued with the upgrade process But error occured.
the main.log file had the following message:
'E:Unable to correct problems, you have held broken packages.'

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.38
ProcVersionSignature: Ubuntu 4.15.0-118.119-generic 4.15.18
Uname: Linux 4.15.0-118-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.17
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Sun Sep 27 12:13:02 2020
InstallationDate: Installed on 2019-09-30 (363 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2020-09-27 (0 days ago)