Update erro

Atingido:1 http://archive.ubuntu.com/ubuntu xenial InRelease
Atingido:2 http://ppa.launchpad.net/embrosyn/cinnamon/ubuntu xenial InRelease
Obter:3 http://archive.ubuntu.com/ubuntu xenial-updates InRelease [95,7 kB]
Atingido:4 http://ppa.launchpad.net/noobslab/themes/ubuntu xenial InRelease
Obter:5 http://archive.ubuntu.com/ubuntu xenial-backports InRelease [92,2 kB]
Obter:6 https://download.01.org/gfx/ubuntu/15.10/main wily InRelease [3.663 B]
Ign:6 https://download.01.org/gfx/ubuntu/15.10/main wily InRelease
Atingido:7 http://archive.ubuntu.com/ubuntu xenial-security InRelease
Baixados 192 kB em 3s (51,5 kB/s)
Lendo listas de pacotes... Pronto
W: Erro GPG: https://download.01.org/gfx/ubuntu/15.10/main wily InRelease: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY A496EB03894A3A8D
W: The repository 'https://download.01.org/gfx/ubuntu/15.10/main wily InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.14
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: X-Cinnamon
Date: Sat Jul 30 10:53:32 2016
InstallationDate: Installed on 2016-05-03 (87 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
Symptom: dist-upgrade
UpgradeStatus: No upgrade log present (probably fresh install)