Xcode "Failed to Prepare Device for Development" Error

The "Failed to prepare device for development" error in Xcode is a common but frustrating issue that can occur when trying to deploy apps to physical iOS devices. This error typically appears with the message: "Errors were encountered while preparing your device for development. Please check the Devices and Simulators Window."

Problem Overview

This error indicates that Xcode cannot properly communicate with your connected iOS device for development purposes. The underlying causes can range from simple connection issues to more complex version incompatibilities between Xcode, macOS, and iOS.

Common Causes

• Version mismatches between Xcode and iOS
• Developer mode disabled on device
• Trust relationship issues between Mac and device
• Network or cable connection problems
• Outdated macOS or Xcode versions
• Connected Apple Watch causing conflicts

Solutions

Quick Fixes to Try First

Before diving into complex solutions, try these simple fixes that often resolve the issue:

Restart Devices

# 1. Restart your iPhone
# 2. Restart your Mac
# 3. Reconnect the USB cable

Basic Xcode Cleanup

# Clean build folder
⌘ + Shift + K

# Alternatively, delete derived data

TIP

Always check the Devices and Simulators window (⌘ + Shift + 2) for detailed error messages that can help identify the specific problem.

Version Compatibility Solutions

The most common cause of this error is version incompatibility between Xcode and iOS.

WARNING

Xcode versions only support iOS versions that were released before or concurrently with that Xcode version.

Solution: Update your software stack

1. Update macOS to the latest compatible version
2. Update Xcode to the latest version from the App Store
3. Update iOS to the latest version on your device

Manual device support installation (if you cannot update Xcode):

If you're stuck with an older Xcode version, you can manually add device support files:

1. Download appropriate device support files from:

   • GitHub: Xcode Developer Disk Images
   • Or GitHub: iOS-DeviceSupport

2. Install them at: Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/

3. Restart Xcode and reconnect your device

Developer Mode and Trust Settings

Ensure proper developer settings on your iOS device:

1. Enable Developer Mode:

   • Go to Settings → Privacy & Security → Developer Mode
   • Toggle on and restart your device when prompted

2. Reset Trust Relationships:

   • On iPhone: Settings → Developer → Clear Trusted Computers
   • Disconnect and reconnect your device
   • Tap "Trust" on the iPhone prompt when reconnecting

3. Check Devices and Simulators Settings:

   • Open Devices window (⌘ + Shift + 2)
   • Ensure "Show run destination" is set to "Always" or "Automatic", not "Never"

Network and Connection Issues

Advanced Network Settings

If using wireless debugging, try disabling multi-path networking:

• On iPhone: Settings → Developer → Disable Multi-Path Networking

Cable and connection troubleshooting:

• Try a different USB cable (some cables are charging-only)
• Try different USB ports on your Mac
• Ensure both devices are on the same WiFi network if using wireless debugging
• For MacBooks, try connecting directly rather than through hubs/docks

Apple Watch Related Issues

If you have an Apple Watch paired to your iPhone, it can sometimes cause conflicts:

1. Unpair Apple Watch from iPhone temporarily
2. Unpair iPhone from Xcode (in Devices window)
3. Restart both devices
4. Re-establish trust relationship with iPhone first
5. Only then repair Apple Watch

Advanced Troubleshooting

If the above solutions don't work, try these advanced steps:

Kill USB Daemon

# Restart the USB daemon without full reboot
sudo killall -STOP -c usbd

Complete Clean Slate

# Comprehensive reset procedure
1. Delete app from device
2. Clean build folder (⌘ + Shift + K)
3. Delete derived data
4. Unpair device from Xcode
5. Restart both devices
6. Re-establish trust

Prevention Tips

1. Keep software updated: Regularly update macOS, Xcode, and iOS
2. Check compatibility: Verify Xcode-iOS compatibility before updating
3. Maintain trust relationships: Avoid frequently switching development computers
4. Use quality cables: Invest in certified USB cables that support data transfer

When to Seek Further Help

If none of these solutions work, consider:

• Checking Apple's Developer Forums for similar issues
• Reviewing Xcode release notes for known bugs
• Filing a bug report with Apple if you suspect a Xcode issue

DANGER

Some older Mac hardware cannot run the latest macOS versions, which may prevent updating to required Xcode versions. Check compatibility before investing significant troubleshooting time.

Remember that Xcode device communication can be fragile, and sometimes simply retrying operations after a brief pause can resolve transient issues.