404 Not Found для do-release-upgrade в Ubuntu [duplicate]

Я использую Ubuntu 15, и я пытаюсь получить Ubuntu 16. Я получал некоторые 404 ошибки с sudo apt-get update, поэтому я уже изучил такие темы, как эти

404 failed to fetch package https://stackoverflow. com/questions/30316812/ubuntu-apt-get-unable-to-fetch-packages

Я устранил ошибки, отредактировав файл /etc/apt/sources.list, чтобы он выглядел так

###### Ubuntu Main Repos
deb-src http://old-releases.ubuntu.com/ubuntu/ wily main restricted universe multiverse 

###### Ubuntu Update Repos
deb http://old-releases.ubuntu.com/ubuntu/ wily-security main restricted universe multiverse 
deb http://old-releases.ubuntu.com/ubuntu/ wily-updates main restricted universe multiverse 
deb-src http://old-releases.ubuntu.com/ubuntu/ wily-security main restricted universe multiverse 
deb-src http://old-releases.ubuntu.com/ubuntu/ wily-updates main restricted universe multiverse 

###### Ubuntu Partner Repo
deb http://archive.canonical.com/ubuntu wily partner
deb-src http://archive.canonical.com/ubuntu wily partner

###### Ubuntu Extras Repo
#deb http://extras.ubuntu.com/ubuntu wily main
#deb-src http://extras.ubuntu.com/ubuntu wily main

Однако, когда я пытаюсь sudo do-release-upgrade, я получаю 404 ошибки, такие как

...
Err http://old-releases.ubuntu.com wily-updates/restricted i386 Packages       
  404  Not Found                                                               
Err http://old-releases.ubuntu.com wily-updates/universe i386     Packages         
  404  Not Found                                                               
Err http://old-releases.ubuntu.com wily-updates/multiverse i386 Packages       
  404  Not Found 

...

Error authenticating some packages 

It was not possible to authenticate some packages. This may be a transient network problem. You may want to try again later. See below  for a list of unauthenticated packages. 

apt-xapian-index 
libboost-graph-parallel1.58.0 
libboost-mpi-python1.58.0 
libboost-mpi1.58.0 
virtualbox 
virtualbox-qt

как это исправить?