Arduino 1.6.8 worked great for a day but suddenly I can’t upload. The error message is go to the troubleshooting guide. One of the solutions is to check my drivers. The guide explains how to do this in Windows but I am on a Mac with El Capitan for OS X. Why I think it might be my drivers is I suddenly have many more serial ports available but none of them work and there is a special mega port that shows up intermittently but it does not work either. I am using an Arduino Mega.
I used to only get one extra serial port besides the usual Apple ports now I have many and have tried them all.