我首先运行sudo apt-get update，然后尝试以下命令，但都失败了
sudo do-release-upgrade
sudo do-release-upgrade -d
sudo do-release-upgrade -p
前面的每个命令都打印相同的消息：
Checking for a new Ubuntu release
No new release found
我试过了sudo apt-get upgrade...没用
我尝试update-manager多次从仪表板运行...没有任何反应
这是输出cat /etc/apt/sources.list
# deb cdrom:[Ubuntu 13.10 _Saucy Salamander_ - Release amd64 (20131016.1)]/ saucy main restricted
deb-src http://archive.ubuntu.com/ubuntu saucy restricted main #Added by software-properties
# deb cdrom:[Ubuntu 13.10 _Saucy Salamander_ - Release amd64 (20131016.1)]/ saucy main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu saucy main restricted
deb-src http://archive.ubuntu.com/ubuntu saucy multiverse universe #Added by software-properties
## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu saucy-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu saucy-updates restricted multiverse main universe #Added by software-properties
## 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://archive.ubuntu.com/ubuntu saucy universe
deb http://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://archive.ubuntu.com/ubuntu saucy multiverse
deb http://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://archive.ubuntu.com/ubuntu saucy-security main restricted
deb-src http://archive.ubuntu.com/ubuntu saucy-security restricted multiverse main universe #Added by software-properties
deb http://archive.ubuntu.com/ubuntu saucy-security universe
deb http://archive.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
## 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
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
## Major bug fix updates produced after the final release of the
## distribution.
## 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.
## 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.
## 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.
## 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-src http://archive.canonical.com/ubuntu saucy partner
## This software is not part of Ubuntu, but is offered by third-party
deb http://archive.canonical.com/ saucy partner
deb-src http://archive.canonical.com/ saucy partner
## developers who want to ship their latest software.
我可能错过了什么？
答案1
我sudo do-release-upgrade昨晚No new release found也试过了，他们告诉我。而且，我发现iso 映像昨天无法下载文件，因为当时那里没有这个文件。
但是今天早上，我发现我可以下载映像 iso 文件，所以......
我通过以下方式成功升级到 14.04sudo do-release-upgrade
再试一次，祝你好运。