Ubuntu 12.04 Failed to download repository information

apt-get update で下のようなエラーがずっと出てて困っていたが、

W:Failed to fetch http://jp.archive.ubuntu.com/ubuntu/dists/precise/main/binary-armhf/Packages  404  Not Found
, W:Failed to fetch http://jp.archive.ubuntu.com/ubuntu/dists/precise/universe/binary-armhf/Packages  404  Not Found
, W:Failed to fetch http://jp.archive.ubuntu.com/ubuntu/dists/precise-updates/main/binary-armhf/Packages  404  Not Found
, W:Failed to fetch http://jp.archive.ubuntu.com/ubuntu/dists/precise-updates/universe/binary-armhf/Packages  404  Not Found
, W:Failed to fetch http://jp.archive.ubuntu.com/ubuntu/dists/precise-backports/main/binary-armhf/Packages  404  Not Found
, W:Failed to fetch http://jp.archive.ubuntu.com/ubuntu/dists/precise-backports/universe/binary-armhf/Packages  404  Not Found
, W:Failed to fetch http://security.ubuntu.com/ubuntu/dists/precise-security/main/binary-armhf/Packages  404  Not Found [IP: 91.189.88.153 80]
, W:Failed to fetch http://security.ubuntu.com/ubuntu/dists/precise-security/universe/binary-armhf/Packages  404  Not Found [IP: 91.189.88.153 80]
, E:Some index files failed to download. They have been ignored, or old ones used instead.

/etc/dpkg/dpkg.cfg.d/multiarch のなかの forein-architecture armhf と書かれた行を消したらエラーが出なくなった。