When running ui tests via cli/fastlane on macOS Big Sur 12.3.0, Xcode 12.5.0
xcodebuild -showBuildSettings -workspace ./MyWorkspace.xcworkspace -scheme MyScheme-UITests
xcodebuild[88311:3500544] DVTErrorPresenter: Unable to load simulator devices.
Domain: DVTCoreSimulatorAdditionsErrorDomain
Code: 3
Failure Reason: The version of the CoreSimulator framework installed on this Mac is out-of-date and not supported by this version of Xcode.
Recovery Suggestion: Please ensure that you have installed all available updates to your Mac's software, and that you are running the most recent version of Xcode supported by macOS.
--
CoreSimulator is out of date. Current version (732.18.6) is older than build version (757.5.0).
Domain: DVTCoreSimulatorAdditionsErrorDomain
Code: 3
--
xcodebuild[88311:3500544] iOSSimulator: [SimServiceContext sharedServiceContextForDeveloperDir:error:] returned nil (Error Domain=DVTCoreSimulatorAdditionsErrorDomain Code=3 "CoreSimulator is out of date.
Current version (732.18.6) is older than build version (757.5.0)."
UserInfo={NSLocalizedDescription=CoreSimulator is out of date. Current version (732.18.6) is older than build version (757.5.0).}). Simulator device support disabled.
What needs to be updated?
It was fixed by tapping "Install components" however I need to figure out what exactly will be installed and if it can be done via cli
As @VictorGazotti said, open Xcode. When it prompts you to install the additional tools, click "Install."
Try the build again.