errori avanzamento

E: Il valore "stable" non è valido per APT::Default-Release poiché tale release non è disponibile dalle sorgenti
E: _cache->open() failed, please report.

W: Duplicate sources.list entry http://it.archive.ubuntu.com/ubuntu/ vivid/main i386 Packages (/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_vivid_main_binary-i386_Packages)
W: Duplicate sources.list entry http://it.archive.ubuntu.com/ubuntu/ vivid/restricted i386 Packages (/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_vivid_restricted_binary-i386_Packages)
W: Duplicate sources.list entry http://it.archive.ubuntu.com/ubuntu/ vivid-updates/main i386 Packages (/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_vivid-updates_main_binary-i386_Packages)
W: Duplicate sources.list entry http://it.archive.ubuntu.com/ubuntu/ vivid-updates/restricted i386 Packages (/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_vivid-updates_restricted_binary-i386_Packages)
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ vivid-security/main i386 Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_vivid-security_main_binary-i386_Packages)
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ vivid-security/restricted i386 Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_vivid-security_restricted_binary-i386_Packages)
W: Duplicate sources.list entry http://archive.canonical.com/ubuntu/ vivid/partner i386 Packages (/var/lib/apt/lists/archive.canonical.com_ubuntu_dists_vivid_partner_binary-i386_Packages)