Comment 1 for bug 1186002

In the "Software & Updates" app (previously named Software Sources), please click the Updates tab and unselect "Pre-released updates (saucy-proposed)". The -proposed repositories are not meant to be used before Ubuntu is officially released as stable since packages there have not been verified to be installable (or pass other tests).

https://lists.ubuntu.com/archives/ubuntu-devel-announce/2012-October/000989.html