apt-get 更新时出现 Ubuntu 16.04 错误

Question

我安装了 Ubuntu 16.04 LTS，当我在终端上插入 # apt-get update 时，它返回这些错误

E: Failed to fetch http://br.archive.ubuntu.com/ubuntu/dists/xenial-updates/main/dep11/Components-amd64.yml.gz  
E: Failed to fetch http://br.archive.ubuntu.com/ubuntu/dists/xenial-updates/universe/dep11/Components-amd64.yml.xz  Hash Sum mismatch
E: Failed to fetch http://br.archive.ubuntu.com/ubuntu/dists/xenial-updates/universe/dep11/icons-64x64.tar.gz  
E: Failed to fetch http://br.archive.ubuntu.com/ubuntu/dists/xenial-updates/multiverse/dep11/Components-amd64.yml.xz  
E: Failed to fetch http://br.archive.ubuntu.com/ubuntu/dists/xenial-backports/main/dep11/Components-amd64.yml.xz  Hash Sum mismatch
E: Failed to fetch http://br.archive.ubuntu.com/ubuntu/dists/xenial-backports/universe/dep11/Components-amd64.yml.xz  
E: Failed to fetch http://br.archive.ubuntu.com/ubuntu/dists/xenial-backports/multiverse/dep11/Components-amd64.yml.xz  
E: Some index files failed to download. They have been ignored, or old ones used instead.

sources.list 如下

#deb cdrom:[Ubuntu 16.04.1 LTS _Xenial Xerus_ - Release amd64 (20160719)]/ xenial main restricted

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

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

## 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
## universe WILL NOT receive any review or updates from the Ubuntu security
## team.
deb http://br.archive.ubuntu.com/ubuntu/ xenial universe
deb-src http://br.archive.ubuntu.com/ubuntu/ xenial universe
deb http://br.archive.ubuntu.com/ubuntu/ xenial-updates universe
deb-src http://br.archive.ubuntu.com/ubuntu/ xenial-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://br.archive.ubuntu.com/ubuntu/ xenial multiverse
deb-src http://br.archive.ubuntu.com/ubuntu/ xenial multiverse
deb http://br.archive.ubuntu.com/ubuntu/ xenial-updates multiverse
deb-src http://br.archive.ubuntu.com/ubuntu/ xenial-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://br.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://br.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe 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 xenial partner
deb-src http://archive.canonical.com/ubuntu xenial partner

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

deb http://members.change-vision.com/repos/apt/ astah main

我的电脑上的操作系统是新的，我只是安装了一些软件。 我从 sources.list 中取出了所有的 deb 和 deb-src 并将最后一行插入到文件中。

我不知道是什么导致了这些错误。

Answer 1

我也遇到了同样的问题。经过大量研究后，对我有用的解决方案是删除所有身份验证密钥（软件源 -> 身份验证，一一删除）。
之后使用 y-ppa-manager 重新安装丢失的密钥。详细操作方法来自here：

1. 要安装它，首先为这个程序添加 webupd8 存储库：
   sudo add-apt-repository ppa:webupd8team/y-ppa-manager

2. 更新您的软件列表并安装 Y-PPA-Manager：
   sudo apt-get update
sudo apt-get install y-ppa-manager

3. 运行 y-ppa-manager（即输入 y-ppa-manager 然后按回车键）。

4. 当 y-ppa-manager 主窗口出现时，点击“高级”。

5. 从高级任务列表中，选择“尝试导入所有缺少的 GPG 键”，然后单击“确定”。

之后只需关闭 y-ppa-manager 并进行更新/升级，现在一切都应该没有错误了。