[Alan Anderson]

I have heard of that error from many teams. I even saw it on our robot once. It seems to have happened when trying to run the program after one of the programmers used the red "stop" button over the Robot Main front panel to abort the program instead of clicking the big "Finish" button. We didn't spend any time trying to make it happen repeatably, so all I have is a hypothesis.

Maybe the invalid relay index happens if you don't close the compressor in the Finish vi before running the program again?