Here’s a simple fix for a common problem that occurs when using older software apps on a new OS.
Concurrent with the release of Final Cut X, Apple discontinued development of its audio editing tool, Soundtrack Pro, that was bundled with earlier versions of the Final Cut Pro suite. If you have Soundtrack Pro installed on an existing OS X 10.6.8 system and then upgrade to Mountain Lion 10.8 and use Migration Assistant to transfer your files and applications, you may encounter the following popup error message when you open the program after the OS upgrade:
Fortunately, there’s a simple fix for this error: It requires deletion of the old plist file associated with the earlier installation of Soundtrack Pro that’s stored in the Library folder of your home directory. The name of the file is com.apple.soundtrackpro.plist. In Mountain Lion, you will need to use one of the standard methods for revealing the hidden Library folder. A simple and direct way to get access to the Library folder is to Option-click the Go menu.
Once you select Library from the drop-down menu, a Finder window will appear onscreen. Navigate the list of folders until you see Preferences. Open the Preferences folder and scroll the list until you see the offending file (com.apple.soundtrackpro.plist). Make sure Soundtrack Pro is not running on your Mac, then trash this file. Now open Soundtrack Pro and see whether the problem has gone away.
in 10.11, the problem seems to be com.apple.spaces.plist as well
I still get the same error opening single waveforms