ubuntu 14.04 sudo apt-get update时，出现404错误。

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/yakkety/universe/binary-amd64/Packages  404  Not Found

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/yakkety/multiverse/binary-amd64/Packages  404  Not Found

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/yakkety/main/binary-i386/Packages  404  Not Found

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/yakkety/universe/binary-i386/Packages  404  Not Found

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/yakkety/multiverse/binary-i386/Packages  404  Not Found

E: Some index files failed to download. They have been ignored, or old ones used instead.

• 原因：http://archive.ubuntu.com/ubuntu/dists/下面压根没有yakkety这个文件夹。
  

  image.png

• 运行sudo vim /etc/apt/sources.list，更换文件的内容如下：

#http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise main
deb-src http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise main


## Major bug fix updates produced after the final release of the
## distribution.
deb http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise-updates main
deb-src http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise-updates main


## 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-east-1.ec2.archive.ubuntu.com/ubuntu/ precise universe
deb-src http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise universe
deb http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise-updates universe
deb-src http://us-east-1.ec2.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.
# deb http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise multiverse
# deb-src http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise multiverse
# deb http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise-updates multiverse
# deb-src http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise-updates multiverse


## Uncomment the following two lines to add software from the 'backports'
## repository.
## 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-east-1.ec2.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse
# deb-src http://us-east-1.ec2.archive.ubuntu.com/ubuntu/ precise-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 precise partner
# deb-src http://archive.canonical.com/ubuntu precise partner


deb http://security.ubuntu.com/ubuntu precise-security main
deb-src http://security.ubuntu.com/ubuntu precise-security main
deb http://security.ubuntu.com/ubuntu precise-security universe
deb-src http://security.ubuntu.com/ubuntu precise-security universe
# deb http://security.ubuntu.com/ubuntu precise-security multiverse
# deb-src http://security.ubuntu.com/ubuntu precise-security multiverse

-重新运行 sudo apt-get update。问题解决。