当从 20 升级到 22 时，我总是有一个未更新的包：
sudo apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
ntp
0 upgraded, 0 newly installed, 0 to remove and **1** not upgraded.
然后当我这样做时：
sudo do-release-upgrade -f DistUpgradeViewGtk3 -d
Checking for a new Ubuntu release
Please install all available updates for your release before upgrading.
它没有这样做，因为它要求安装所有可用的更新。这是一条通知，因为我已经完成了更新和升级。当我尝试时：
apt list --upgradable
Listing... Done
ntp/focal-updates,focal-security 1:4.2.8p12+dfsg-3ubuntu4.20.04.1 amd64 [upgradable from: 1:4.2.8p12+dfsg-3ubuntu3]
N: There are 2 additional versions. Please use the '-a' switch to see them.
焦点安全似乎是问题所在。我不知道如何克服这个问题并获得版本 22.04 LTS。欢迎任何帮助。