Xcode Simulator Not Launching or Won't Boot

How to fix it

Try these in order — the most common fix is first.

1. 1. Restart the simulator service

   Copy steps
   1. Quit Xcode and Device Hub / Simulator
   2. In Terminal run: xcrun simctl shutdown all
   3. Run: sudo killall -9 com.apple.CoreSimulator.CoreSimulatorService
   4. Reopen Xcode and run the app again
   Did this fix it? Yes No

2. 2. Erase the failing simulator

   Copy steps
   1. Run: xcrun simctl list devices to find the device
   2. Run: xcrun simctl erase <device-UDID> (or xcrun simctl erase all)
   3. Boot it again from Xcode's run destination menu
   Did this fix it? Yes No

3. 3. Reinstall the runtime

   Copy steps
   1. Open Xcode > Settings > Components
   2. Delete the affected iOS runtime
   3. Download it again and wait for verification to finish
   4. Confirm with xcrun simctl runtime list
   Did this fix it? Yes No

4. 4. Use Device Hub on Xcode 27

   Copy steps
   1. Open Xcode > Open Developer Tool > Device Hub
   2. Select the simulator under Simulators and boot it from there
   3. Update any script that calls open -a Simulator to use xcrun simctl boot <UDID>
   Did this fix it? Yes No

5. 5. Free disk space and update

   Copy steps
   1. Make sure at least 20 GB is free
   2. Install the newest Xcode point release; several boot failures are fixed in later 27.x builds
   Did this fix it? Yes No

Symptoms

The simulator window never appears, stays black or stuck on the Apple logo, or Xcode reports 'Unable to boot device' or 'Data Migration Failed'. On Xcode 27, Simulator.app is replaced by Device Hub, so scripts that run open -a Simulator also fail.

Why it happens

• Corrupted simulator device data
• iOS runtime not fully installed or mismatched with the Xcode version
• CoreSimulator service stuck from a previous crash
• Not enough free disk space
• Tools or scripts still calling Simulator.app on Xcode 27 (now Device Hub)

This guide also covers

• xcode simulator not launching
• xcode unable to boot device
• simulator stuck on apple logo
• xcode simulator won't open

Other Xcode errors

• Xcode 'Unable to Install' App Error
• Xcode 'No Profiles Found' Code Signing Error
• Xcode 'Failed to Register Bundle Identifier' Error
• Xcode Indexing Stuck or Taking Forever
• Xcode Doesn't Show My iPhone (Device Not Detected)
• Xcode Taking Too Much Storage (How to Free 50GB+)
• Xcode 'Build Failed' With No Clear Error
• Xcode SwiftUI Preview Not Working or Crashing