updated 10:50 am EDT, Tue August 19, 2014
Workaround involves manually launching dispatcher service
Yesterday's Developer Preview 6 release of OS X Yosemite is breaking Parallels Desktop 9, users report. After DP6 is installed, Desktop 9 is simply refusing to run, exactly the type of issue beta testers routinely encounter. The problem appears to involve the dispatcher service failing to load, as a temporary solution involves forcing the service to start via a Terminal command. This again has been seen in various other apps not yet updated for the forthcoming Yosemite.
Parallels Desktop 9 is an OS virtualization app for the Mac that lets users run Windows apps without having to boot into a separate partition. Given its popularity, fixing compatibility will likely be a high priority for Parallels before the next developer preview is released, or at least before the gold master.