I've got XCode 9 beta building my project but then I get an alert: "Error returned in reply: Connection Invalid - Software caused connection abort"
Launching the simulator from the tools menu shows the frame with the Apple logo as if it's booting.
Trying to change devices in the simulator gives "Error returned in reply: Connection invalid".
I still have XCode 8 installed but have tried rebooting and launching directly into beta 9 with the same results.