如图

先尝试常见解决方案


另一种可能是：



参考
http://ubuntuforums.org/showthread.php?t=863742
https://bugs.launchpad.net/ubuntu/+source/apt/+bug/346386
http://askubuntu.com/questions/30072/how-do-i-fix-a-problem-with-mergelist-or-status-file-could-not-be-parsed-err
http://askubuntu.com/questions/454895/update-manager-bug-encountered-a-section-with-no-package-header

感谢楼上，15。04也是经常坏掉

W: 无法下载 cdrom://Ubuntu 14.04.3 LTS _Trusty Tahr_ - Beta amd64 (20150805)/dists/trusty/main/binary-amd64/Packages 请使用 apt-cdrom，通过它就可以让 APT 能识别该盘片。apt-get upgdate 不能被用来加入新的盘片。

W: 无法下载 cdrom://Ubuntu 14.04.3 LTS _Trusty Tahr_ - Beta amd64 (20150805)/dists/trusty/restricted/binary-amd64/Packages 请使用 apt-cdrom，通过它就可以让 APT 能识别该盘片。apt-get upgdate 不能被用来加入新的盘片。

W: 无法下载 cdrom://Ubuntu 14.04.3 LTS _Trusty Tahr_ - Beta amd64 (20150805)/dists/trusty/main/binary-i386/Packages 请使用 apt-cdrom，通过它就可以让 APT 能识别该盘片。apt-get upgdate 不能被用来加入新的盘片。

W: 无法下载 cdrom://Ubuntu 14.04.3 LTS _Trusty Tahr_ - Beta amd64 (20150805)/dists/trusty/restricted/binary-i386/Packages 请使用 apt-cdrom，通过它就可以让 APT 能识别该盘片。apt-get upgdate 不能被用来加入新的盘片。

W: 无法下载 http://cn.archive.ubuntu.com/ubuntu/dis ... tion-zh_CN 错误的报头行 [IP: 112.124.140.210 80]

W: 无法下载 http://cn.archive.ubuntu.com/ubuntu/dis ... tion-en_US 错误的报头行 [IP: 112.124.140.210 80]

W: 无法下载 http://cn.archive.ubuntu.com/ubuntu/dis ... slation-en 错误的报头行 [IP: 112.124.140.210 80]

E: 部分索引文件下载失败。如果忽略它们，那将转而使用旧的索引文件。

安装新立得之后系统就不行了

deb cdrom:[Ubuntu 14.04.3 LTS _Trusty Tahr_ - Beta amd64 (20150805)]/ trusty main restricted

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

## Major bug fix updates produced after the final release of the
## distribution.
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-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://cn.archive.ubuntu.com/ubuntu/ trusty universe
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty universe
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-updates universe
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-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://cn.archive.ubuntu.com/ubuntu/ trusty multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-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://security.ubuntu.com/ubuntu trusty-security main restricteddeb cdrom:[Ubuntu 14.04.3 LTS _Trusty Tahr_ - Beta amd64 (20150805)]/ trusty main restricted

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

## Major bug fix updates produced after the final release of the
## distribution.
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-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://cn.archive.ubuntu.com/ubuntu/ trusty universe
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty universe
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-updates universe
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-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://cn.archive.ubuntu.com/ubuntu/ trusty multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-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://security.ubuntu.com/ubuntu trusty-security main restricted
deb-src http://security.ubuntu.com/ubuntu trusty-security main restricted
deb http://security.ubuntu.com/ubuntu trusty-security universe
deb-src http://security.ubuntu.com/ubuntu trusty-security universe
deb http://security.ubuntu.com/ubuntu trusty-security multiverse
deb-src http://security.ubuntu.com/ubuntu trusty-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 trusty partner
# deb-src http://archive.canonical.com/ubuntu trusty 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 trusty main
deb-src http://extras.ubuntu.com/ubuntu trusty main
deb-src http://security.ubuntu.com/ubuntu trusty-security main restricted
deb http://security.ubuntu.com/ubuntu trusty-security universe
deb-src http://security.ubuntu.com/ubuntu trusty-security universe
deb http://security.ubuntu.com/ubuntu trusty-security multiverse
deb-src http://security.ubuntu.com/ubuntu trusty-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 trusty partner
# deb-src http://archive.canonical.com/ubuntu trusty 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 trusty main
deb-src http://extras.ubuntu.com/ubuntu trusty main

//gedit /etc/apt/sources.list

把 "deb cdrom:" 开头的行注释掉？


网络问题居多。换源，挂代理或等几天再试
也可 sudo rm -vf /var/lib/apt/lists/* 再试，不过一般无效果



参考
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=365819
http://aptosid.com/index.php?name=PNphpBB2&file=viewtopic&t=2834

更新里面 勾选了可从光驱安装。。。然后去掉了 就没问题了