The fix is to edit /etc/apt/sources.list.d/elementary.list and change anywhere it says "luna" to "precise"
If you have added any PPAs, you'll need to fix those as well. They live in: /etc/apt/sources.list.d/
Some of them will need "luna" changed to "precise" and some of them will need "sid" changed to "precise"
The fix is to edit /etc/apt/ sources. list.d/ elementary. list and change anywhere it says "luna" to "precise" sources. list.d/
If you have added any PPAs, you'll need to fix those as well. They live in: /etc/apt/
Some of them will need "luna" changed to "precise" and some of them will need "sid" changed to "precise"