Error: Could not reset simulator. Leaving as is. Error: Command failed: // stderr:

when I use appium 1.3.1 run test on ios Simulator,I got this error:
error: Could not reset simulator. Leaving as is. Error: Command failed: // stderr:

info: [debug] Cleaning app data files
warn: Applications directory /Users/wensujian815/Library/Developer/CoreSimulator/Devices/BADD1264-38A2-4066-988C-F656F0C0EFF1/data/Containers/Data/Application doesn’t exist. Have you run this simulator before?
warn: Applications directory /Users/wensujian815/Library/Developer/CoreSimulator/Devices/BADD1264-38A2-4066-988C-F656F0C0EFF1/data/Containers/Bundle/Application doesn’t exist. Have you run this simulator before?
info: Couldn’t find app directories to delete. Probably it’s not installed
info: [debug] Cleaning up appium session
info: [debug] Responding to client with success: {“status”:0,“value”:null,“sessionId”:“97508a9b-9866-435e-be39-d04921a2e430”}
info: <-- DELETE /wd/hub/session/97508a9b-9866-435e-be39-d04921a2e430 200 3444.896 ms - 76 {“status”:0,“value”:null,“sessionId”:“97508a9b-9866-435e-be39-d04921a2e430”}

how to solve this problem,thanks.

I had to restart xcode / my machine to bring the simulator back up