Do you have a .als file from 2012 sitting on a hard drive? If you open it in Live 12 without the Legacy Pack, you will get "Missing Device" errors. The legacy pack restores those exact algorithms so your old track sounds exactly as you left it.
See how to manage and install legacy content directly within your current Ableton library: Using Live Packs in Live 8 and 9 subaqueousmusic YouTube• Sep 24, 2013 ableton live 8 legacy pack
If you are a modern producer using Live 11 or 12, is there any reason to install 10+ year old sounds? Do you have a