I have found others asking the same question, suddenly your Arduino USB port becomes disabled and you can no longer upload your sketch.
Error shows as: can't open device "/dev/cu.usbmodem14201": No such file or directory
The problem occurs when you draw too much power from your USB connected Arduino. I suspected this because it occurred when I set my LED strip to max brightness. Dimming the brightness solved the issue.
Once the board is kicked out of the bus you need to unplug-replug your USB cable.