Failed to load iOS Simulator; launchdd failed to respond

I have a problem: when starting the simulator, a black screen appears with the message: "Unable to load iOS Simulator". I am using Xcode 6.4 with iOS 8.4 Simulator.

I tried several solutions that are suggested on other threads, but nothing seems to work. (startd.conf not found on my system) Is there any solution without reinstalling Xcode / OS X?

Log file:

Jul 8 15:10:07 WMUCM482679 CoreSimulatorService [793]: Could not register service com.apple.PowerManagement.control: start_sim_register_endpoint: 0xfffffecc Jul 8 15:10:17 WMUCM482679 CoreSimulatorService [793]: Failed to register com.apple.SystemConstruction service .configd_host: start_sim_register_endpoint: 0xfffffecc Jul 8 15:10:27 WMUCM482679 CoreSimulatorService [793]: Failed to register service com.apple.audio.coreaudiod: launch_sim_register_endpoint: 0xfffffecc Jul 8 15:10:37 CoreSimulator could not register WMUCM482679 service com.apple.SystemConfiguration.PPPC controller: start_sim_register_endpoint: 0xfffffecc Jul 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: Failed to register service com.apple.audio.audiohald: launch_sim_register_endpoint: 0x44e Jul 8 15:1037 WMUCM482679 CoreSimulatorService [793]: Failed to register service com.apple.coreservices.lsuseractivity.simulatorsupport: start_sim_register_endpoint: 0x44e Jul 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: Failed to register service com.apple_endsister_register 444 July 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: failed to register service com.apple.SystemConfiguration.configd: start_sim_register_endpoint: 0x44e July 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: failed to register service IndigoHIDRegistrationPort44: failed to register service IndigoHIDRegistrationPort44 Jul 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: PurpleFBTVOutServer registration service failed: launch_sim_register_endpoint: 0x44e Jul 8 15:10:37 WMUCM482679 CoreSimulatorService [793]:Failed to register PurpleFBServer service: start_sim_register_endpoint: 0x44e Jul 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: Domain error = NSPOSIXErrorDomain Code = 60 "Unable to load iOS Simulator". UserInfo = 0x7f8c70d18fd0 {NSLocalizedDescription = Unable to load iOS Simulator., NSLocalizedFailureReason = launchd could not respond.} Jul 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: Error Domain = NSPOSIXErrorDomain Code = 60 "Unable to load iOS Simulator = 60" UserInfo = 0x7f8c70d18fd0 {NSLocalizedDescription = Unable to load iOS Simulator., NSLocalizedFailureReason = launchd could not respond.} Jul 8 15:10:37 WMUCM482679 com.apple.iphonesimulator [902]: Error Domain = NSPOSIXErrorDomain Code = 60 "Unable to load iOS Simulator" ...UserInfo = 0x7fcf53a01aa0 {NSLocalizedDescription = Unable to load iOS Simulator., NSLocalizedFailureReason = launchd could not respond.} Jul 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: Error Domain = com.apple.CoreSimulator.SimError Code = 146 to current state: Shutdown "UserInfo = 0x7f8c70d18fd0 {NSLocalizedDescription = Unable to search in current state: Shutdown} Jul 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: Error finding host support portUserInfo = 0x7f8c70d18fd0 {NSLocalizedDescription = Unable to search in current state: Shutdown} Jul 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: Error finding host support portUserInfo = 0x7f8c70d18fd0 {NSLocalizedDescription = Could not search in current state: Shutdown} Jul 8 15:10:37 WMUCM482679 CoreSimulatorService [793]: Error finding host support port