automatic update from ubuntu 18 (bionic beaver) to ubuntu 20 always fail

[Bahtiar Ependi]

when the automatic update was in progress, always appear a fail notification and the update was be cancelled.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.30 [origin: unknown]
ProcVersionSignature: Ubuntu 4.18.0-15.16~18.04.1-generic 4.18.20
Uname: Linux 4.18.0-15-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CrashDB: ubuntu
Date: Sun Jan 16 19:53:57 2022
InstallationDate: Installed on 2019-06-22 (939 days ago)
InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2022-01-16 (0 days ago)
VarLogDistupgradeAptlog:
 Log time: 2022-01-16 19:47:45.817764
 Log time: 2022-01-16 19:48:14.186209
 Log time: 2022-01-16 19:53:33.460127
 Log time: 2022-01-16 19:54:04.442445
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

The mirror of the Ubuntu archive which you use does not seem to be accessible any more and that is preventing your ability to upgrade to the next release of Ubuntu. I suggest switching mirrors of the Ubuntu archive and then updating all the packages for your existing release of Ubuntu and then trying the upgrade process again.

2022-01-16 19:48:51,830 DEBUG examining: 'deb http://kambing.ui.ac.id/ubuntu/ bionic main universe restricted multiverse'
2022-01-16 19:48:51,833 DEBUG verifySourcesListEntry: deb http://kambing.ui.ac.id/ubuntu/ focal main universe restricted multiverse
2022-01-16 19:48:51,833 DEBUG url_downloadable: http://kambing.ui.ac.id/ubuntu//dists/focal/Release
2022-01-16 19:48:51,833 DEBUG s='http' n='kambing.ui.ac.id' p='/ubuntu//dists/focal/Release' q='' f=''
2022-01-16 19:48:52,975 DEBUG error from httplib: '[Errno 104] Connection reset by peer'
2022-01-16 19:48:52,976 DEBUG entry '# deb http://kambing.ui.ac.id/ubuntu/ bionic main universe restricted multiverse' was disabled (no Release file)
2022-01-16 19:48:52,976 DEBUG examining: 'deb-src http://kambing.ui.ac.id/ubuntu/ bionic main universe restricted multiverse #Added by software-properties'
2022-01-16 19:48:52,979 DEBUG entry '# deb-src http://kambing.ui.ac.id/ubuntu/ bionic main universe restricted multiverse #Added by software-properties' was disabled (no Release file)
2022-01-16 19:53:33,330 DEBUG running doUpdate() (showErrors=True)

[Launchpad Janitor (janitor)]

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