Failed to boot IBSimDeviceTypeiPad2x

Question

Accessing storyboard hangs xcode, then throws error below. This happens for newly created project, on newly (re)installed xcode.

I've tried xcrun simctl commands, there is no device with UDID: 9C08E254-108D-49F6-A1FC-CE43B2F30EB9.

Not clear which device IBSimDeviceTypeiPad2x is.

Deleted and recreated all iPad devices in Simulator. iPad 2 is not possible on iOS 11.4

Have already done complete uninstall and reinstall of xcode (including removing ~/Library/Developer / Cache / Application Support stuff.

Problem persists.

Error:

Encountered an error communicating with Interface Builder Cocoa Touch Tool. 
(Failure reason: Interface Builder Cocoa Touch Tool failed to launch):
Failed to boot device IBSimDeviceTypeiPad2x (9C08E254-108D-49F6-A1FC-CE43B2F30EB9, iOS 11.4, Shutdown)


System content for IBCocoaTouchFramework-ElevenAndLater <IBScaleFactorDeviceTypeDescription: 
0x7f93a450bec0> scaleFactor=2x (Failure reason: Failed to boot IBSimDeviceTypeiPad2x (9C08E254-108D-49F6-A1FC-CE43B2F30EB9, iOS 11.4, Shutdown)): 
Unable to boot the Simulator. (Failure reason: launchd failed to respond.)

launchd_sim log contains:

missing or invalid configuration plist

xcode version:

Version = 9.4.1 (9F2000)
Plugin Version = 14113
Beta Version = 0
OS Version = 10.13.6 (17G65)

Answer 1

I have been struggling with this for some time, filed a bug report with Apple and they claimed I didn't have permission. No reference to what permissions. Towards the bottom of the log file from the bug report was the following text.

"You don’t have permission to save the file “60ACC3A5-E7E2-4330-869B-15447826C019” in the folder “CoreSimulator”." UserInfo={NSFilePath=/Users/terryburdett/Library/Logs/CoreSimulator/60ACC3A5-E7E2-4330-869B-15447826C019, NSUnderlyingError=0x7fda1871c8b0 {Error Domain=NSPOSIXErrorDomain Code=13 "Permission denied"}}}}}

Follow the path to Logs and getinfo on Logs folder. If your name isn't in the sharing and permissions list, unlock the folder and add it. Change permissions to read/write. Next time you run Xcode it should create an CoreSimulator folder in the Logs folder and compile without bug.

Answer 2

In case this helps anyone else with this issue: after weeks of back and forth with Apple Support, we tracked this down to either third party kernel extensions or third-party antivirus. After thoroughly ensuring both were disabled, Storyboard editing became available again. In my case, it was most likely Little Snitch that was interfering (make sure both Network Filter & Network Monitor are set to the "off" position). There could potentially be a Little Snitch rule that's interfering as well, I haven't spent enough time to track it down yet.