我无法让 16.04 LTS 到 18.04.1 LTS 升级正常工作，我正在运行服务器。
我的当前版本：
lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.5 LTS
Release: 16.04
Codename: xenial
但是尽管 18.04.1 于 7 月 26 日发布，但目前在 31 日我仍然被告知没有新版本？
我的/etc/update-manager/release-upgrades文件是：
# 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
输出如下do-release-upgrade：
Checking for a new Ubuntu release
No new release found.
更新管理器核心已安装：
sudo apt install update-manager-core
Reading package lists... Done
Building dependency tree
Reading state information... Done
update-manager-core is already the newest version (1:16.04.13).
0 to upgrade, 0 to newly install, 0 to remove and 0 not to upgrade.
请注意，这个问题与这里的问题不同我是否应该可以选择升级到 18.04.1？因为该问题涉及基于 GUI/桌面的情况，而这个是从终端/服务器角度专门解决问题的。
答案1
预计 18.04.1 发布后几天才会启用 16.04 LTS 的升级。八月初。 https://wiki.ubuntu.com/BionicBeaver/ReleaseSchedule