可能重复：
如何安装软件或从旧的不受支持的版本升级？
我正在尝试从 10.04 升级到 12.04。
设置新的软件频道时出现以下错误：
W：获取失败http://us.archive.ubuntu.com/ubuntu/dists/karmic/main/source/Sources 404 未找到 [IP: 91.189.91.15 80]，W：无法获取http://us.archive.ubuntu.com/ubuntu/dists/karmic/restricted/source/Sources 404 未找到 [IP: 91.189.91.15 80] ......................... 七个以上此类错误 ......................... , E:某些索引文件下载失败。它们已被忽略，或使用旧文件代替。
并且升级过程停止。
先感谢您。
答案1
看起来你正在使用因果考拉（9.10）存储库。由于 Karmic 不再受支持，您的系统无法更新。
如果您使用的是 10.04，请尝试禁用这些存储库。如需更多信息，您能否附上您的 sources.list 文件？使用此命令并粘贴输出：
猫/etc/apt/sources.list
added by the release upgrader
deb cdrom:[Ubuntu 9.10 Karmic Koala - Release i386 (20091027)]/ karmic main restricted
deb cdrom:[Ubuntu 8.10 Intrepid Ibex - Release i386 (20081030)]/ intrepid main restricted
See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
newer versions of the distribution.
deb http://us.archive.ubuntu.com/ubuntu/ lucid main restricted deb-src http://us.archive.ubuntu.com/ubuntu/ lucid main restricted
Major bug fix updates produced after the final release of the
distribution.
deb http://us.archive.ubuntu.com/ubuntu/ lucid-updates main restricted deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-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://us.archive.ubuntu.com/ubuntu/ lucid universe deb-src http://us.archive.ubuntu.com/ubuntu/ lucid universe deb http://us.archive.ubuntu.com/ubuntu/ lucid-updates universe deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-updates universe
deb http://cran.opensourceresources.org/bin/linux/ubuntu jaunty/ # disabled on upgrade to karmic
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.archive.ubuntu.com/ubuntu/ lucid multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ lucid multiverse deb http://us.archive.ubuntu.com/ubuntu/ lucid-updates multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-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.archive.ubuntu.com/ubuntu/ intrepid-backports main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ intrepid-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 intrepid partner
deb-src http://archive.canonical.com/ubuntu intrepid partner
deb http://ppa.launchpad.net/dell-team/ubuntu jaunty main # disabled on upgrade to jaunty
deb-src http://ppa.launchpad.net/dell-team/ubuntu jaunty main # disabled on upgrade to jaunty
deb http://kondr.ic.cz/deb lucid main # disabled on upgrade to karmic
deb http://kondr.ic.cz/deb lucid main # disabled on upgrade to karmic
deb http://us.archive.ubuntu.com/ubuntu/ lucid-proposed restricted main multiverse universe deb http://us.archive.ubuntu.com/ubuntu/ lucid-backports restricted main multiverse universe deb http://security.ubuntu.com/ubuntu/ lucid-security restricted main multiverse universe deb http://kondr.ic.cz/deb lucid main deb http://cran.stat.unipd.it/bin/linux/ubuntu lucid/