Symptom:
X11/XQuartz error when trying to open Caldera.
This problem could happen when XQuartz has been updated or received an incomplete update.
Problem:
Caldera requires Xquartz but is only compatible with XQuartz 2.7.9.
Downloaded and (re)install XQuartz 2.7.9
and reboot the computer.
Background info: As Caldera is a Linux based application it's using X Windows.