Last month, one morning, my MacBook (still running Catalina) started behaving strangely - though I was not running anything, it was sluggish as the CPU was too busy and the fans were on high. I traced it to the iOS Simulator service that comes with XCode.

The logging tool (weirdly called Console.app), had crash reports EXEC_CRASH. Obviously, com.apple.CoreSimulator.CoreSimulatorService was stuck in a crash loop (start.. crash, start... crash, start... crash, back off for a while... and repeat):

Console Log com.apple.CoreSimulator.CoreSimulatorService crash

I have no idea what caused it, since I haven’t used XCode in ages. I also don’t find any update around that time (System Information.app > Software > Installations sorted by Install Date).

Anyway, simulator commands that may help someone are:

  • xcrun simctl list - List available devices, device types, runtimes, or device pairs.
  • xcrun simctl delete unavailable all - Delete spcified devices, unavailable devices, or all devices.
  • xcrun simctl erase all - Erase a device's contents and settings.

For me, I also got rid of XCode, and re-installed it. So far so good...

The spelling mistake above is as per the description in the xcrun help.