error while upgrade ubuntu 18 LTS to 20 LTS: comm: /var/log/dmesg: No such file or directory

[TuD]

I want to upgrade my Ubuntu 18.04.5 LTS to 20.04.1 LTS, but got this:

Hit http://archive.canonical.com/ubuntu focal InRelease
Fetched 0 B in 0s (0 B/s)

Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done

Invalid package information

After updating your package information, the essential package
'ubuntu-minimal' could not be located. This may be because you have
no official mirrors listed in your software sources, or because of
excessive load on the mirror you are using. See /etc/apt/sources.list
for the current list of configured software sources.
In the case of an overloaded mirror, you may want to try the upgrade
again later.

Restoring original system state

Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
name:~$ comm: /var/log/dmesg: No such file or directory

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.38
ProcVersionSignature: Ubuntu 5.4.0-47.51~18.04.1-generic 5.4.55
Uname: Linux 5.4.0-47-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.17
Architecture: amd64
CrashDB: ubuntu
Date: Tue Sep 8 20:07:46 2020
InstallationDate: Installed on 2019-12-21 (262 days ago)
InstallationMedia: Ubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2020-09-08 (0 days ago)
VarLogDistupgradeAptlog:
 Log time: 2020-09-08 20:07:25.300955
 Log time: 2020-09-08 20:07:30.323355
 Log time: 2020-09-08 20:07:45.988139
 Log time: 2020-09-08 20:07:50.051624

[Brian Murray (brian-murray)]

I suspect this is because you have configured your sources.list file to communicate via ftp.

2020-09-08 20:07:42,661 DEBUG Checking pkg: ubuntu-standard
2020-09-08 20:07:42,664 DEBUG examining: 'deb ftp://ftp.fu-berlin.de/linux/ubuntu/ bionic main restricted'
2020-09-08 20:07:42,664 DEBUG verifySourcesListEntry: deb ftp://ftp.fu-berlin.de/linux/ubuntu/ focal main restricted
2020-09-08 20:07:42,664 DEBUG url_downloadable: ftp://ftp.fu-berlin.de/linux/ubuntu//dists/focal/Release
2020-09-08 20:07:42,664 DEBUG s='ftp' n='ftp.fu-berlin.de' p='/linux/ubuntu//dists/focal/Release' q='' f=''
2020-09-08 20:07:42,840 DEBUG error from ftplib: '550 SIZE not allowed in ASCII mode'
2020-09-08 20:07:42,841 DEBUG entry '# deb ftp://ftp.fu-berlin.de/linux/ubuntu/ bionic main restricted' was disabled (no Release file)
2020-09-08 20:07:42,842 DEBUG examining: 'deb ftp://ftp.fu-berlin.de/linux/ubuntu/ bionic-updates main restricted'
2020-09-08 20:07:42,842 DEBUG entry '# deb ftp://ftp.fu-berlin.de/linux/ubuntu/ bionic-updates main restricted' was disabled (no Release file)

Please switch to using http and try the upgrade again.

[Launchpad Janitor (janitor)]

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