Xcode "Failed to Prepare Device for Development" Error

Problem Statement

When attempting to run an iOS application on a physical device, developers frequently encounter the error: "Failed to prepare device for development." This typically occurs with the following message:

"This operation can fail if the version of the OS on the device is incompatible with the installed version of Xcode. You may also need to restart your Mac and device in order to correctly detect compatibility."

This compatibility issue commonly arises when your Xcode version doesn't include support files for the specific iOS version installed on your device.

Root Cause

Xcode requires specific device support files for each iOS version to communicate with physical devices. When these files are missing or incompatible, Xcode cannot properly prepare the device for development, resulting in the error.

Solutions

1. Update Xcode (Recommended)

The most straightforward solution is ensuring you have the latest Xcode version that supports your device's iOS version:

Xcode Version Compatibility

• Check Apple's official Xcode release notes for compatibility information
• Visit the App Store and search for Xcode to check for updates
• Note: The App Store may not always show updates automatically; manually search if needed

2. Add Missing Device Support Files

If updating Xcode isn't immediately possible, you can manually add the required device support files:

1. Navigate to the DeviceSupport directory:

   /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/

2. Check if a folder exists for your iOS version (e.g., "15.4")

3. If missing, download the appropriate support files from:

   • filsv/iOSDeviceSupport
   • JinjunHan/iOSDeviceSupport (for newer versions)

4. Extract the downloaded ZIP file and place the folder in the DeviceSupport directory

5. Restart Xcode and reconnect your device

Version Naming

Ensure the folder name exactly matches your iOS version. For example, if your device runs iOS 16.4.1, the folder must be named "16.4.1" (not just "16.4").

3. Restart Devices

Sometimes, simple restarts can resolve connection issues:

1. Restart your iPhone/iPad
2. Restart your Mac
3. Reconnect the device and try again

This approach resolved the issue for many developers, particularly when all software was already up-to-date.

4. Enable Developer Mode (iOS 16+)

For devices running iOS 16 or later, ensure Developer Mode is enabled:

1. Go to Settings > Privacy & Security > Developer Mode
2. Toggle Developer Mode on
3. Restart your device when prompted

5. Reset Location & Privacy Settings

If trust issues persist between your device and Mac:

1. On your iOS device, go to Settings > General > Transfer or Reset [Device]
2. Tap Reset > Reset Location & Privacy
3. Enter your passcode to confirm
4. Reconnect your device and re-establish trust

6. Complete Device Reset (Last Resort)

For persistent issues, particularly with iOS 17 and Xcode 15:

1. Backup your device
2. Go to Settings > General > Transfer or Reset [Device] > Erase All Content and Settings
3. Set up your device and reconnect to Xcode

Data Loss Warning

This will erase all data on your device. Ensure you have a recent backup before proceeding.

Special Cases

Xcode 14 and iOS 15.7 Incompatibility

Apple has documented a specific incompatibility between Xcode 14 and iOS 15.7. The official workaround is to use Xcode 13.4.1 with iOS 15.7 devices.

Beta Version Considerations

When working with beta software:

• Xcode betas may be required for iOS beta versions
• Be aware of known issues in beta release notes
• Consider stable versions for production development

Troubleshooting Steps

If you continue to experience issues:

1. Check console errors: Look for specific error messages in Xcode's console
2. Verify cable connection: Try a different USB cable or port
3. Clean build: Use ⌘ + ⇧ + K to clean build folder
4. Delete derived data: Remove old build artifacts
5. Check trust settings: Ensure you've tapped "Trust" on your device when connecting

Prevention

To avoid this issue in the future:

• Keep Xcode updated to the latest stable version
• Regularly check for iOS and Xcode compatibility before updating devices
• Maintain backups of important device support files for older iOS versions

By following these solutions, most developers can resolve the "Failed to prepare device for development" error and continue testing their applications on physical devices.