我正在尝试从lubuntu 13.10升级到14.04

apt-get update
apt-get dist-upgrade  
do-release-upgrade

但是最后一条命令返回 No new release found

我也尝试do-release-upgrade -d了相同的结果。

/etc/apt/sources.list 看起来像：

# deb cdrom:[Lubuntu 13.10 _Saucy Salamander_ - Release amd64 (20131016.1)]/ saucy main multiverse restricted universe

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://de.archive.ubuntu.com/ubuntu/ saucy main restricted
deb-src http://de.archive.ubuntu.com/ubuntu/ saucy main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://de.archive.ubuntu.com/ubuntu/ saucy-updates main restricted
deb-src http://de.archive.ubuntu.com/ubuntu/ saucy-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://de.archive.ubuntu.com/ubuntu/ saucy universe
deb-src http://de.archive.ubuntu.com/ubuntu/ saucy universe
deb http://de.archive.ubuntu.com/ubuntu/ saucy-updates universe
deb-src http://de.archive.ubuntu.com/ubuntu/ saucy-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
## team, and may not be under a free licence. Please satisfy yourself as to 
## your rights to use the software. Also, please note that software in 
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://de.archive.ubuntu.com/ubuntu/ saucy multiverse
deb-src http://de.archive.ubuntu.com/ubuntu/ saucy multiverse
deb http://de.archive.ubuntu.com/ubuntu/ saucy-updates multiverse
deb-src http://de.archive.ubuntu.com/ubuntu/ saucy-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://de.archive.ubuntu.com/ubuntu/ saucy-backports main restricted universe multiverse
deb-src http://de.archive.ubuntu.com/ubuntu/ saucy-backports main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu saucy-security main restricted
deb-src http://security.ubuntu.com/ubuntu saucy-security main restricted
deb http://security.ubuntu.com/ubuntu saucy-security universe
deb-src http://security.ubuntu.com/ubuntu saucy-security universe
deb http://security.ubuntu.com/ubuntu saucy-security multiverse
deb-src http://security.ubuntu.com/ubuntu saucy-security multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
deb http://archive.canonical.com/ubuntu saucy partner
# deb-src http://archive.canonical.com/ubuntu saucy partner

## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
deb http://extras.ubuntu.com/ubuntu saucy main
deb-src http://extras.ubuntu.com/ubuntu saucy main

deb http://ppa.launchpad.net/stebbins/handbrake-releases/ubuntu raring main
deb-src http://ppa.launchpad.net/stebbins/handbrake-releases/ubuntu raring main
deb http://dl.google.com/linux/earth/deb/ stable main
# deb-src http://archive.canonical.com/ubuntu saucy partner

请注意，我只是使用相同的服务器升级了lubuntu，而没有问题。

文件内容 /etc/update-manager/meta-releases

# default location for the meta-release file

[METARELEASE]
URI = http://changelogs.ubuntu.com/meta-release
URI_LTS = http://changelogs.ubuntu.com/meta-release-lts
URI_UNSTABLE_POSTFIX = -development
URI_PROPOSED_POSTFIX = -proposed

/etc/update-manager/release-upgrades 看起来像：

# some comments...

Prompt=normal

我也改变normal为lts没有成功。

我还检查了目录/var/lib/ubuntu-release-upgrader/为空。

也没有proxy文件，/etc/apt/apt.conf.d/因此似乎没有使用代理。

该文件/etc/hosts如下所示：

127.0.0.1       localhost
127.0.1.1       mybox

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

因此，我尝试了发行版升级问题“找不到新版本”中的所有解决方案，但均未成功。

知道这里可能有什么问题吗？

编辑

使用图形界面，update-manager我收到错误消息：“无法下载存储库信息”

也许这为您提供了解决问题的提示。

编辑2

我现在从去服务器切换成主服务器和从我删除了所有的PPA sources.list和sources.list.d。如果可能，请使用ppa-purge。如果没有，我会用适当的方法清除相关的软件包，然后删除ppa条目。

PPA的也正是关于下列程序包：sagemath，google-earth，handbrake，freetuxtv和julia（数学程序）。

但是没有成功。

对我来说，原因是我禁用了自动检查升级功能，因为该check-new-release过程一直在极大地降低计算机的速度。

变回Prompt=normal在/etc/update-manager/release-upgrades瞬间解决了这一问题。

终于成功了。问题是我do-release-upgrade以root用户身份进行操作，但这没有用。以普通用户的身份调用此命令。但是，我不明白为什么它不是root。

尝试这个！！！

剪切并粘贴以下全部命令：

sudo apt-get clean ;
cd /var/lib/apt ;
sudo mv lists lists.old_`date '+%Y%m%d_%H%M%S'`   ;
sudo mkdir -p lists/partial ;
sudo apt-get clean ;
sudo apt-get update

用分号分隔每个命令，以便可以将它们粘贴在一起。之后，执行以下操作：

sudo apt-get clean
sudo do apt-get update
sudo apt-get dist-upgrade  
sudo do-release-upgrade

如果失败，请执行以下操作：

sudo sed -i 's/saucy/trusty/g' /etc/apt/sources.list
sudo apt-get update
sudo apt-get upgrade 

注意：删除所有第三方PPA，除非它们具有14.04版本。如果您有Gnome PPA，请使用PPA-Purge删除它。

您需要检查以下选项：

然后do-release-upgrade再次启动

从终端或统一启动器运行命令：gksu update-manager -d。如果尝试运行sudo update-manager -d，它并不总是提供14.04可用选项。但是对于gksu，此选项将出现。

否则，请创建可启动的USB驱动器。使用相同的方式启动，并在安装时选择升级或其他方式。在其他情况下，请为/，swap交换安装点早于相同的驱动器。取消选择格式选项。不要选择格式。这将保留您的所有文件和以前的设置并进行升级。

谢谢。

最近，我还受到“找不到新版本”的困扰，事实证明这是一个连通性问题。我们的防火墙根据此Snort / Suricata规则阻止了该请求：

ET POLICY Python-urllib/ Suspicious User Agent

我知道这不是您的问题，但希望它能帮助另一个问题。