我尝试过sudo do-release-upgrade，但失败并出现以下错误
Calculating the changes
Calculating the changes
Could not calculate the upgrade
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'.
Restoring original system state
Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
处的输出/var/log/dist-upgrade/main.log如下
2020-10-18 20:54:09,188 INFO Using config files '['./DistUpgrade.cfg.bionic']'
2020-10-18 20:54:09,188 INFO uname information: 'Linux not-script-kiddie 5.4.0-48-generic #52~18.04.1-Ubuntu SMP Thu Sep 10 12:50:22 UTC 2020 x86_64'
2020-10-18 20:54:09,609 INFO apt version: '1.6.12ubuntu0.1'
2020-10-18 20:54:09,609 INFO python version: '3.6.9 (default, Jul 17 2020, 12:50:27)
[GCC 8.4.0]'
2020-10-18 20:54:09,613 INFO release-upgrader version '20.04.28' started
2020-10-18 20:54:09,624 INFO locale: 'en_IN' 'ISO8859-1'
2020-10-18 20:54:09,670 INFO screen could not be run
2020-10-18 20:54:09,702 DEBUG Using 'DistUpgradeViewText' view
2020-10-18 20:54:09,749 DEBUG enable dpkg --force-overwrite
2020-10-18 20:54:09,778 DEBUG creating statefile: '/var/log/dist-upgrade/apt-clone_system_state.tar.gz'
2020-10-18 20:54:14,187 DEBUG lsb-release: 'bionic'
2020-10-18 20:54:14,187 DEBUG _pythonSymlinkCheck run
2020-10-18 20:54:14,188 DEBUG openCache()
2020-10-18 20:54:14,188 DEBUG quirks: running PreCacheOpen
2020-10-18 20:54:14,188 DEBUG running Quirks.PreCacheOpen
2020-10-18 20:54:15,314 DEBUG Comparing 4.15.0-118 with
2020-10-18 20:54:15,332 DEBUG Comparing 5.4.0-47 with 4.15.0-118
2020-10-18 20:54:15,332 DEBUG Comparing 5.4.0-48 with 5.4.0-47
2020-10-18 20:54:15,594 DEBUG /openCache(), new cache size 100437
2020-10-18 20:54:15,595 DEBUG need_server_mode(): can not find a desktop meta package or key deps, running in server mode
2020-10-18 20:54:15,595 DEBUG checkViewDepends()
2020-10-18 20:54:15,677 DEBUG running doUpdate() (showErrors=False)
2020-10-18 20:54:31,823 DEBUG openCache()
2020-10-18 20:54:33,115 DEBUG Comparing 4.15.0-118 with
2020-10-18 20:54:33,121 DEBUG Comparing 5.4.0-47 with 4.15.0-118
2020-10-18 20:54:33,122 DEBUG Comparing 5.4.0-48 with 5.4.0-47
2020-10-18 20:54:33,484 DEBUG /openCache(), new cache size 100757
2020-10-18 20:54:33,484 DEBUG doPostInitialUpdate
2020-10-18 20:54:33,484 DEBUG quirks: running focalPostInitialUpdate
2020-10-18 20:54:33,484 DEBUG running Quirks.focalPostInitialUpdate
2020-10-18 20:54:37,160 DEBUG MetaPkgs:
2020-10-18 20:54:42,777 DEBUG Foreign: bluetooth bluez bluez-cups bluez-obexd cuda-repo-ubuntu1604 google-chrome-stable libbluetooth3 libcudnn7 libcudnn7-dev libvdpau1 libvulkan1 nvidia-machine-learning-repo-ubuntu1604 nvidia-opencl-icd-440 sublime-text teams teamviewer vdpau-driver-all
2020-10-18 20:54:42,777 DEBUG Obsolete: cuda-repo-ubuntu1604-9-0-local libcudnn7-doc zoom
2020-10-18 20:54:42,778 DEBUG updateSourcesList()
2020-10-18 20:54:42,817 DEBUG rewriteSourcesList() with mirror_check
2020-10-18 20:54:42,817 DEBUG ['ubuntu-minimal', 'ubuntu-standard']
2020-10-18 20:54:42,817 DEBUG Checking pkg: ubuntu-minimal
2020-10-18 20:54:42,820 DEBUG Checking pkg: ubuntu-standard
2020-10-18 20:54:42,822 DEBUG examining: 'deb http://it-mirrors.evowise.com/ubuntu/ bionic main restricted'
2020-10-18 20:54:42,823 DEBUG verifySourcesListEntry: deb http://it-mirrors.evowise.com/ubuntu/ focal main restricted
2020-10-18 20:54:42,823 DEBUG url_downloadable: http://it-mirrors.evowise.com/ubuntu//dists/focal/Release
2020-10-18 20:54:42,823 DEBUG s='http' n='it-mirrors.evowise.com' p='/ubuntu//dists/focal/Release' q='' f=''
2020-10-18 20:54:43,384 DEBUG entry 'deb http://it-mirrors.evowise.com/ubuntu/ focal main restricted' updated to new dist
2020-10-18 20:54:43,384 DEBUG examining: 'deb http://it-mirrors.evowise.com/ubuntu/ bionic-updates main restricted'
2020-10-18 20:54:43,386 DEBUG entry 'deb http://it-mirrors.evowise.com/ubuntu/ focal-updates main restricted' updated to new dist
2020-10-18 20:54:43,386 DEBUG examining: 'deb http://it-mirrors.evowise.com/ubuntu/ bionic universe'
2020-10-18 20:54:43,387 DEBUG entry 'deb http://it-mirrors.evowise.com/ubuntu/ focal universe' updated to new dist
2020-10-18 20:54:43,388 DEBUG examining: 'deb http://it-mirrors.evowise.com/ubuntu/ bionic-updates universe'
2020-10-18 20:54:43,389 DEBUG entry 'deb http://it-mirrors.evowise.com/ubuntu/ focal-updates universe' updated to new dist
2020-10-18 20:54:43,389 DEBUG examining: 'deb http://it-mirrors.evowise.com/ubuntu/ bionic multiverse'
2020-10-18 20:54:43,390 DEBUG entry 'deb http://it-mirrors.evowise.com/ubuntu/ focal multiverse' updated to new dist
2020-10-18 20:54:43,390 DEBUG examining: 'deb http://it-mirrors.evowise.com/ubuntu/ bionic-updates multiverse'
2020-10-18 20:54:43,392 DEBUG entry 'deb http://it-mirrors.evowise.com/ubuntu/ focal-updates multiverse' updated to new dist
2020-10-18 20:54:43,392 DEBUG examining: 'deb http://it-mirrors.evowise.com/ubuntu/ bionic-backports main restricted universe multiverse'
2020-10-18 20:54:43,393 DEBUG entry 'deb http://it-mirrors.evowise.com/ubuntu/ focal-backports main restricted universe multiverse' updated to new dist
2020-10-18 20:54:43,393 DEBUG examining: 'deb http://it-mirrors.evowise.com/ubuntu/ bionic-security main restricted'
2020-10-18 20:54:43,394 DEBUG entry 'deb http://it-mirrors.evowise.com/ubuntu/ focal-security main restricted' updated to new dist
2020-10-18 20:54:43,394 DEBUG examining: 'deb http://it-mirrors.evowise.com/ubuntu/ bionic-security universe'
2020-10-18 20:54:43,396 DEBUG entry 'deb http://it-mirrors.evowise.com/ubuntu/ focal-security universe' updated to new dist
2020-10-18 20:54:43,396 DEBUG examining: 'deb http://it-mirrors.evowise.com/ubuntu/ bionic-security multiverse'
2020-10-18 20:54:43,397 DEBUG entry 'deb http://it-mirrors.evowise.com/ubuntu/ focal-security multiverse' updated to new dist
2020-10-18 20:54:43,397 DEBUG examining: 'deb [arch=amd64] https://repo.skype.com/deb stable main'
2020-10-18 20:54:43,399 DEBUG entry '# deb [arch=amd64] https://repo.skype.com/deb stable main # disabled on upgrade to focal' was disabled (unknown mirror)
2020-10-18 20:54:43,399 DEBUG examining: 'deb [arch=amd64] https://packages.microsoft.com/repos/ms-teams stable main'
2020-10-18 20:54:43,400 DEBUG entry '# deb [arch=amd64] https://packages.microsoft.com/repos/ms-teams stable main # disabled on upgrade to focal' was disabled (unknown mirror)
2020-10-18 20:54:43,400 DEBUG examining: 'deb http://ppa.launchpad.net/bluetooth/bluez/ubuntu bionic main'
2020-10-18 20:54:43,401 DEBUG entry '# deb http://ppa.launchpad.net/bluetooth/bluez/ubuntu focal main # disabled on upgrade to focal' was disabled (unknown mirror)
2020-10-18 20:54:43,401 DEBUG examining: 'deb http://ppa.launchpad.net/graphics-drivers/ppa/ubuntu bionic main'
2020-10-18 20:54:43,402 DEBUG entry '# deb http://ppa.launchpad.net/graphics-drivers/ppa/ubuntu focal main # disabled on upgrade to focal' was disabled (unknown mirror)
2020-10-18 20:54:43,402 DEBUG examining: 'deb file:///var/cuda-repo-9-0-local /'
2020-10-18 20:54:43,403 DEBUG entry '# deb file:///var/cuda-repo-9-0-local / # disabled on upgrade to focal' was disabled (unknown mirror)
2020-10-18 20:54:43,403 DEBUG examining: 'deb http://developer.download.nvidia.com/compute/machine-learning/repos/ubuntu1604/x86_64 /'
2020-10-18 20:54:43,404 DEBUG entry '# deb http://developer.download.nvidia.com/compute/machine-learning/repos/ubuntu1604/x86_64 / # disabled on upgrade to focal' was disabled (unknown mirror)
2020-10-18 20:54:43,404 DEBUG examining: 'deb https://download.sublimetext.com/ apt/stable/'
2020-10-18 20:54:43,405 DEBUG entry '# deb https://download.sublimetext.com/ apt/stable/ # disabled on upgrade to focal' was disabled (unknown mirror)
2020-10-18 20:54:43,405 DEBUG examining: 'deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main'
2020-10-18 20:54:43,406 DEBUG entry '# deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main # disabled on upgrade to focal' was disabled (unknown mirror)
2020-10-18 20:54:43,406 DEBUG examining: 'deb http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1604/x86_64 /'
2020-10-18 20:54:43,408 DEBUG entry '# deb http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1604/x86_64 / # disabled on upgrade to focal' was disabled (unknown mirror)
2020-10-18 20:54:43,408 DEBUG examining: 'deb http://linux.teamviewer.com/deb stable main'
2020-10-18 20:54:43,409 DEBUG entry '# deb http://linux.teamviewer.com/deb stable main # disabled on upgrade to focal' was disabled (unknown mirror)
2020-10-18 20:54:57,582 DEBUG running doUpdate() (showErrors=True)
2020-10-18 20:55:20,273 DEBUG openCache()
2020-10-18 20:55:21,086 DEBUG Comparing 4.15.0-118 with
2020-10-18 20:55:21,087 DEBUG Comparing 5.4.0-47 with 4.15.0-118
2020-10-18 20:55:21,087 DEBUG Comparing 5.4.0-48 with 5.4.0-47
2020-10-18 20:55:21,271 DEBUG /openCache(), new cache size 66663
2020-10-18 20:55:21,272 DEBUG need_server_mode(): can not find a desktop meta package or key deps, running in server mode
2020-10-18 20:55:21,274 DEBUG quirks: running PreDistUpgradeCache
2020-10-18 20:55:21,275 DEBUG running Quirks.PreDistUpgradeCache
2020-10-18 20:55:21,275 INFO checking for python-dbg
2020-10-18 20:55:21,275 INFO checking for python-doc
2020-10-18 20:55:21,275 INFO checking for python-minimal
2020-10-18 20:55:21,275 INFO installing python-is-python2 because python-minimal was installed
2020-10-18 20:55:21,275 DEBUG Installing 'python-is-python2' (python-minimal was installed on the system)
2020-10-18 20:55:21,631 ERROR Dist-upgrade failed: 'E:Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.'
2020-10-18 20:55:21,633 DEBUG abort called
2020-10-18 20:55:21,636 DEBUG openCache()
2020-10-18 20:55:26,258 DEBUG Comparing 4.15.0-118 with
2020-10-18 20:55:26,263 DEBUG Comparing 5.4.0-47 with 4.15.0-118
2020-10-18 20:55:26,263 DEBUG Comparing 5.4.0-48 with 5.4.0-47
2020-10-18 20:55:26,527 DEBUG /openCache(), new cache size 100757