Erro no VirtualBox ao atualizar

Question

Aqui está o erro quando tento atualizar:

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.

Este é o conteúdo de /etc/apt/sources.list :

# 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

Alguém pode ajudar?

    

Answer 1

Este é um problema em que uma das suas fontes está desatualizada ou corrompida para corrigir:

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

E tente a atualização novamente

    

Answer 2

(Wrong sources.list entry or malformed file)

Tente esta correção

exclua o sources.list porque está corrompido.

sudo rm /etc/apt/sources.list

faça o download de um novo. abrindo propriedades de software

sudo software-properties-gtk 

marque as caixas: conforme abaixo na captura de tela. Mude o servidor principal para o seu país. Então clique em Fechar

Emseguida,umaoutrajanelaseráexibida.vocêquerclicaremrecarregar.

Quando isso for feito, tente atualizar