Unable to upgrade due to bad mirror

[SATYANANDA KAR]

during manual upgradation. Please provide me an graphical upgradation.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.37
ProcVersionSignature: Ubuntu 4.15.0-108.109-generic 4.15.18
Uname: Linux 4.15.0-108-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.15
Architecture: amd64
CrashDB: ubuntu
Date: Thu Jun 25 18:02:22 2020
InstallationDate: Installed on 2019-02-14 (496 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=en_IN
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2020-06-25 (0 days ago)
VarLogDistupgradeAptlog:
 Log time: 2020-06-25 17:57:38.470755
 Log time: 2020-06-25 18:01:26.186896
 Log time: 2020-06-25 18:02:22.639249
 Log time: 2020-06-25 18:02:24.615852

[Brian Murray (brian-murray)]

The mirror of the Ubuntu archive which you use is not accessible. Please switch to an official mirror of the Ubuntu archive and try the upgrade again.

2020-06-25 18:01:45,990 DEBUG examining: 'deb http://repo.iitd.ernet.in/ubuntu bionic main restricted universe multiverse'
2020-06-25 18:01:45,993 DEBUG verifySourcesListEntry: deb http://repo.iitd.ernet.in/ubuntu focal main restricted universe multiverse
2020-06-25 18:01:45,993 DEBUG url_downloadable: http://repo.iitd.ernet.in/ubuntu/dists/focal/Release
2020-06-25 18:01:45,993 DEBUG s='http' n='repo.iitd.ernet.in' p='/ubuntu/dists/focal/Release' q='' f=''
2020-06-25 18:02:16,020 DEBUG error from httplib: '<urlopen error [Errno -2] Name or service not known>'
2020-06-25 18:02:16,020 DEBUG entry '# deb http://repo.iitd.ernet.in/ubuntu bionic main restricted universe multiverse' was disabled (no Release file)

[Launchpad Janitor (janitor)]

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