更新时VirtualBox错误

Question

下面是我尝试更新时的错误：

W: Failed to fetch http://download.virtualbox.org/virtualbox/debian/dists/vivid/InRelease  Unable to find expected entry 'contrib/source/Sources' in Release file (Wrong sources.list entry or malformed file)

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

以下是/etc/apt/sources.list的内容：

# deb cdrom:[Ubuntu-MATE 15.04 _Vivid Vervet_ - Release amd64 (20150422.1)]/ vivid main multiverse restricted universe

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

## Major bug fix updates produced after the final release of the
## distribution.
deb http://gb.archive.ubuntu.com/ubuntu/ vivid-updates main restricted
deb-src http://gb.archive.ubuntu.com/ubuntu/ vivid-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 
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://gb.archive.ubuntu.com/ubuntu/ vivid multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ vivid multiverse
deb http://gb.archive.ubuntu.com/ubuntu/ vivid-updates multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ vivid-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://gb.archive.ubuntu.com/ubuntu/ vivid-backports main restricted multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ vivid-backports main restricted multiverse

deb http://security.ubuntu.com/ubuntu vivid-security main restricted
deb-src http://security.ubuntu.com/ubuntu vivid-security main restricted
deb http://security.ubuntu.com/ubuntu vivid-security multiverse
deb-src http://security.ubuntu.com/ubuntu vivid-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 vivid partner
deb-src http://archive.canonical.com/ubuntu vivid partner

有人能帮忙吗？

Answer 1

如果您的某个源已经过时或损坏以修复此问题，则此问题：

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

然后再尝试更新。

Answer 2

(Wrong sources.list entry or malformed file)

试试这个修补程序

删除sources.list，因为它损坏了。

sudo rm /etc/apt/sources.list

然后再下载一个新的。通过开放软件属性

sudo software-properties-gtk 

勾选方框:如下图所示。将主服务器更改为您的国家。然后单击“关闭”

然后另一扇窗户就会爆开。你想要点击重新加载。

完成后，试着更新