我正在尝试从 升级Ubuntu 16.04.5 LTS到18.04。我运行了sudo do-release-upgrade，大约 1 小时后，该过程完成：
Processing triggers for resolvconf (1.79ubuntu10) ...
Errors were encountered while processing:
kubuntu-desktop
Exception during pm.DoInstall(): E:Sub-process /usr/bin/dpkg returned an error code (1)
Could not install the upgrades
The upgrade has aborted. Your system could be in an unusable state. A
recovery will run now (dpkg --configure -a).
dpkg: dependency problems prevent configuration of kubuntu-desktop:
kubuntu-desktop depends on software-properties-kde; however:
Package software-properties-kde is not installed.
dpkg: error processing package kubuntu-desktop (--configure):
dependency problems - leaving unconfigured
Errors were encountered while processing:
kubuntu-desktop
Upgrade complete
The upgrade has completed but there were errors during the upgrade
process.
To continue please press [ENTER]
我重新启动后，我的 Linux 似乎出现了问题18.04，所以我以为只是kubuntu-desktop安装失败了。我尝试强制安装它：
sudo apt-get install -f kubuntu-desktop
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
kubuntu-desktop : Depends: software-properties-kde but it is not going to be installed
Recommends: apport-kde but it is not going to be installed
Recommends: kubuntu-driver-manager but it is not going to be installed
Recommends: kubuntu-notification-helper but it is not going to be installed
Recommends: muon but it is not going to be installed
Recommends: plasma-discover but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
下面我总是尝试强制安装未满足的依赖项：
kubuntu-desktop-> software-properties-kde->-> python3-pyqt5-> libpython3.6->libpython3.6-stdlib
当我尝试安装时，libpython3.6-stdlib我得到：
Reading package lists... Done
Building dependency tree
Reading state information... Done
libpython3.6-stdlib is already the newest version (3.6.7-1+xenial1).
0 upgraded, 0 newly installed, 0 to remove and 9 not upgraded.
有谁遇到过类似的问题吗？