Xcode tests won't run on device or CircleCI "Early unexpected exit"

[200ok]

Locally, tests will run and pass on Simulator

And locally, tests will “appear” to have run when running with a device, but the log reveals they aren’t actually running and it says “Failed to establish communication with the test runner”

CircleCI fails saying “Early unexpected exit, operation never finished bootstrapping - no restart will be attempted”

[09:48:21]: ▸ 2019-01-17 09:48:21.372 xcodebuild[617:5252] [MT] IDETestOperationsObserverDebug: 0.000 sec, +0.000 sec – start
[09:48:21]: ▸ 2019-01-17 09:48:21.372 xcodebuild[617:5252] [MT] IDETestOperationsObserverDebug: 39.914 sec, +39.914 sec – end
[09:48:21]: ▸ 2019-01-17 09:48:21.373 xcodebuild[617:5252] Error Domain=IDETestOperationsObserverErrorDomain Code=6 “Early unexpected exit, operation never finished bootstrapping - no restart will be attempted” UserInfo={NSLocalizedDescription=Early unexpected exit, operation never finished bootstrapping - no restart will be attempted, NSUnderlyingError=0x7fbe07968350 {Error Domain=IDETestOperationsObserverErrorDomain Code=5 “Test runner exited before starting test execution.” UserInfo={NSLocalizedDescription=Test runner exited before starting test execution., NSLocalizedRecoverySuggestion=If you believe this error represents a bug, please attach the result bundle at /Users/distiller/Library/Developer/Xcode/DerivedData/DebuggingCircleCI-dfqeecacsvjhpgbevfephjqspusi/Logs/Test/Run-DebuggingCircleCI-2019.01.17_09-47-08–0800.xcresult}}}
[09:48:21]: ▸ Testing failed:
[09:48:21]: ▸ DebuggingCircleCI.app (1194) encountered an error (Early unexpected exit, operation never finished bootstrapping - no restart will be attempted. Underlying error: Test runner exited before starting test execution.)

[200ok]

So, doing a “reset and erase all settings” on the iPad does allow tests to run on the iPad. Not sure what was going on. Even a blank/new Xcode project would fail before. Now, after updating the config.yml in my main project to xcode: "10.1.0" it’s running and passing on CircleCI, too. So… now nobody touch anything! It’s perfect. : )