我不能把Ubuntu 18.04升级到20

Question

软件和更新未显示。从航站楼->

kristina@kristina-desktop:~$ sudo apt install update-manager
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package update-manager is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'update-manager' has no installation candidate

我想先升级到Ubuntu 20，然后是22

Answer 1

我花了3个小时就能解决问题，我下载了Bionic.zip并将/apt从它复制到了/etc。我什么都能做。经过长期的斗争，我的问题就这样解决了。