我已经跑了
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
并认为已经解决了所有错误，但现在运行时sudo do-release-upgrade仍然出现：
Checking for a new Ubuntu release
Please install all available updates for your release before upgrading.
apt-get-update：
root@shop-update:/# apt-get update
Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [107 kB]
Ign:2 http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.2 InRelease
Hit:3 http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.2 Release
Hit:5 http://ppa.launchpad.net/certbot/certbot/ubuntu xenial InRelease
Hit:6 https://repos.sonar.digitalocean.com/apt main InRelease
Hit:7 https://deb.nodesource.com/node_6.x xenial InRelease
Hit:8 http://nyc2.mirrors.digitalocean.com/ubuntu xenial InRelease
Hit:9 http://nyc2.mirrors.digitalocean.com/ubuntu xenial-updates InRelease
Hit:10 http://nyc2.mirrors.digitalocean.com/ubuntu xenial-backports InRelease
Fetched 107 kB in 1s (97.4 kB/s)
Reading package lists... Done
apt-get 升级：
root@shop-update:/# apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
cloud-init
0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
答案1
升级被阻止，因为 apt-get upgrade 的输出显示：
以下软件包已被保留：（
部分软件包列表）
你应该首先解决这个问题。如果你打算安装“保留”的软件包，请参阅此答案：