Error message: System ran out of critical resources, you must reboot your Mac!

If you have an Apogee Ensemble or Element Thunderbolt unit, the following error message may appear:

This is a warning to let you know that the computer is in a state where the System RAM is not optimized for digital audio performance, and the Mac should be restarted.

Close/QUIT all apps running on your computer, then do a full restart of your computer to resolve this.