O Ubuntu não conseguiu atualizar a versão mais recente

Question

Eu sou novo no sistema operacional Ubuntu. Eu estou tentando atualizar da versão 14.04 para 16.04. Mas não é capaz de atualizar a versão mais recente.

Abaixo, recebi a mensagem durante a atualização, por isso fiz alterações em sources.list usando o link .

Could not calculate the upgrade 

An unresolvable problem occurred while calculating the upgrade. 

This can be caused by: 
* Upgrading to a pre-release version of Ubuntu 
* Running the current pre-release version of Ubuntu 
* Unofficial software packages not provided by Ubuntu 

Mas o arquivo sources.list não está sendo atualizado corretamente. O arquivo mostra como:

###### Ubuntu Main Repos
deb http://in.archive.ubuntu.com/ubuntu/ xenial main
deb-src http://in.archive.ubuntu.com/ubuntu/ xenial main

###### Ubuntu Update Repos
deb http://in.archive.ubuntu.com/ubuntu/ xenial-updates main
deb-src http://in.archive.ubuntu.com/ubuntu/ xenial-updates main
:wq
:wq!
:wq

E o meu arquivo original sources.list foi assim:

# deb cdrom:[Ubuntu 14.04.1 LTS _Trusty Tahr_ - Release amd64 (20140722.2)]/ trusty main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://in.archive.ubuntu.com/ubuntu/ trusty main restricted
deb-src http://in.archive.ubuntu.com/ubuntu/ trusty main restricted universe multiverse #Added by software-properties

## Major bug fix updates produced after the final release of the
## distribution.
deb http://in.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb-src http://in.archive.ubuntu.com/ubuntu/ trusty-updates main restricted universe multiverse #Added by software-properties

## 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://in.archive.ubuntu.com/ubuntu/ trusty universe
deb http://in.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://in.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://in.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://in.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://in.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse #Added by software-properties

deb http://in.archive.ubuntu.com/ubuntu/ trusty-security main restricted
deb-src http://in.archive.ubuntu.com/ubuntu/ trusty-security main restricted universe multiverse #Added by software-properties
deb http://in.archive.ubuntu.com/ubuntu/ trusty-security universe
deb http://in.archive.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 http://www.rabbitmq.com/debian/ stable main

# deb http://downloads.sourceforge.net/project/sonar-pkg/deb trusty main

deb http://in.archive.ubuntu.com/ubuntu/ trusty-proposed restricted main universe multiverse

Enfrentando problemas no upgarde e para alterações incorretas.