I was updating my XCode installation today, and got a prompt from the installer asking me to quit iTunes in order for the installer to be able to continue. Trouble was iTunes was not running!
It turns out that what it meant to say was “go on
htop or Activity Monitor, look for anything that looks like it has something to do with iTunes and kill it, cause I need to do some stuff that you wouldn’t understand”.
Quick look on
htop told me that the problem was the iTunesHelper startup item, and killing that sorted the installer out.