需要安装不受信任的软件包？

Question

我昨天尝试安装 VLC Player，但Requires installation of untrusted packages出现错误。我搜索了几个小时来解决这个问题，最后得到一个建议，说要更改服务器以从中下载更新。我这样做了，当我单击更新管理器中的“检查”时，它给了我 404 错误。我尝试将我的服务器切换回主服务器（之后，还有其他几个），但我现在仍然收到 404 错误：

下载或更新时遇到的另一个错误：

编辑：输出cat /etc/apt/sources.list：

deb-src http://us.archive.ubuntu.com/ubuntu/ precise main restricted #Added by software-properties

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://us.archive.ubuntu.com/ubuntu/ precise main restricted multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ precise multiverse universe #Added by software-properties

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

## 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://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 #Added by software-properties

deb http://us.archive.ubuntu.com/ubuntu/ precise-security main restricted multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ precise-security restricted main multiverse universe #Added by software-properties
deb http://us.archive.ubuntu.com/ubuntu/ precise-security universe

## 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 precise partner
deb-src http://archive.canonical.com/ubuntu precise partner

## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.

Answer 1

根据您在我之前回答的评论部分粘贴的错误，我有另一个可能的解决方案：

sudo apt-get clean
cd /var/lib/apt
sudo mv lists lists.old
sudo mkdir -p lists/partial
sudo apt-get clean 
sudo apt-get update

这将重建缓存。
礼貌：http : //ubuntuforums.org/showthread.php? t= 1983220#8

Answer 2

此链接可能会有所帮助。它解决了一个非常相似的问题。

基本上，您打开一个终端并输入sudo apt-get update && sudo apt-get upgrade. 那是为我做的。

Answer 3

接受的答案在我的情况下（Ubuntu 13.10）对我没有帮助，但我能够解决通过命令行而不是通过软件更新程序更新的问题（以防其他人遇到这个问题）。

sudo aptitude upgrade

向我展示了来自不受信任的来源（Google 的音乐管理器）的特定软件包，并询问我是否愿意接受并升级。