buendia@buendia-X550CC:~$ sudo apt update && sudo apt upgrade
[sudo] password di buendia: 
Ign:1 http://archive.canonical.com/ubuntu saucy InRelease
Trovato:2 http://security.ubuntu.com/ubuntu artful-security InRelease          
Err:3 http://archive.canonical.com/ubuntu saucy Release                        
  404  Not Found [IP: 91.189.91.15 80]
Trovato:4 http://it.archive.ubuntu.com/ubuntu artful InRelease
Trovato:5 http://it.archive.ubuntu.com/ubuntu artful-updates InRelease
Lettura elenco dei pacchetti... Fatto                
E: The repository 'http://archive.canonical.com/ubuntu saucy Release' no longer has a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.