2015 年初（注意，这是 2016 年 10 月），我的许多服务器从 12.04 升级到 14.04，没有出现任何问题。几年前我更新过几十个类似的系统，总的来说，我从来没有遇到过这样的问题。
我现在正在尝试运行一台服务器，但它给出了“未找到新版本”的错误。
我只是好奇我是否遗漏了什么，或者在过去一年左右更新方法是否发生了变化。你有什么想法吗？
$ sudo do-release-grade
Checking for a new Ubuntu release
No new release found
$ lsb_release-a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 12.04.5 LTS
Release: 12.04
Codename: precise
/etc/apt/source.列表：
deb http://us.archive.ubuntu.com/ubuntu/ precise main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ precise main restricted
deb http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted
deb http://us.archive.ubuntu.com/ubuntu/ precise universe
deb-src http://us.archive.ubuntu.com/ubuntu/ precise universe
deb http://us.archive.ubuntu.com/ubuntu/ precise-updates universe
deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates universe
deb http://us.archive.ubuntu.com/ubuntu/ precise multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ precise multiverse
deb http://us.archive.ubuntu.com/ubuntu/ precise-updates multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates multiverse
deb http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu precise-security main restricted
deb-src http://security.ubuntu.com/ubuntu precise-security main restricted
deb http://security.ubuntu.com/ubuntu precise-security universe
deb-src http://security.ubuntu.com/ubuntu precise-security universe
deb http://security.ubuntu.com/ubuntu precise-security multiverse
deb-src http://security.ubuntu.com/ubuntu precise-security multiverse
/etc/update-manager/release-upgrades
# Default behavior for the release upgrader.
[DEFAULT]
# Default prompting behavior, valid options:
#
# never - Never check for a new release.
# normal - Check to see if a new release is available. If more than one new
# release is found, the release upgrader will attempt to upgrade to
# the release that immediately succeeds the currently-running
# release.
# lts - Check to see if a new LTS release is available. The upgrader
# will attempt to upgrade to the first LTS release available after
# the currently-running one. Note that this option should not be
# used if the currently-running release is not itself an LTS
# release, since in that case the upgrader won't be able to
# determine if a newer release is available.
Prompt=lts
答案1
我遇到了同样的问题，但刚刚解决了。
请确保在实际升级之前完成此操作。
sudo apt-get update
sudo apt-get upgrade
首先解决此时遇到的问题。
然后，您可能会在运行 时遇到“未找到新版本” sudo do-release-upgrade。sudo apt-get install update-manager在 之前尝试sudo do-release-upgrade。这解决了我的问题。