Migration Assistant transfers most of your files, apps, and settings, but not everything

Migration Assistant is Apple's built-in tool for moving data from an old Mac to a new one. It copies your user account, installed applications, documents, photos, music, and system settings. However, it does not transfer some categories of data — certain app-specific files, some security settings, and content stored only in cloud services. Understanding what moves and what does not helps you plan what to handle separately.

The tool works by connecting your old Mac to your new one over a network or through a direct cable, then copying everything from your user library and Applications folder. The process typically takes several hours depending on how much data you have. Most people find that after Migration Assistant finishes, their new Mac looks and behaves almost identically to the old one — but a few things require manual attention.

Key Takeaways

  • Migration Assistant moves user files, applications, photos, music, email accounts, and system preferences, but leaves behind some app-specific data and security settings.
  • Passwords stored in Keychain transfer over, but two-factor authentication codes and some app-specific passwords may not, so plan to re-enter those separately.
  • Files stored only in cloud services like iCloud Drive, Google Drive, or Dropbox do not transfer — they sync automatically once you sign in to your account on the new Mac.
  • Some older applications may not work on a new Mac if the operating system version is significantly different, even though Migration Assistant copies them.
  • You can run Migration Assistant multiple times if you forget something, though it is easier to transfer everything once and delete what you do not want afterward.

What Migration Assistant does transfer

Migration Assistant copies your entire user account, which includes your home folder with all documents, downloads, desktop files, and the Library folder where most applications store their settings. It transfers installed applications from your Applications folder, so you do not have to download and reinstall them individually. Your email accounts, contacts, calendar events, and Safari bookmarks move over with their associated data.

System settings transfer as well — your display preferences, keyboard shortcuts, printer configurations, network settings, and accessibility options all move to the new Mac. Photos and music in your local library (not just cloud copies) transfer completely. Keychain, which stores passwords for websites and networks, transfers to the new Mac, so you do not have to re-enter every password you use regularly.

If you have multiple user accounts on your old Mac, you can choose to transfer all of them or only specific ones. Migration Assistant also preserves file permissions and ownership, so shared folders and restricted files maintain their access rules on the new machine.

What does not transfer and why

Files that exist only in cloud storage — such as Google Drive, Dropbox, OneDrive, or iCloud Drive — do not transfer because they are not stored on your Mac's hard drive. Instead, they sync automatically once you sign in to your account on the new Mac. This is actually safer than transferring them, because it ensures you have the latest version from the cloud rather than an older local copy.

Some applications store data outside the standard locations that Migration Assistant checks. Certain games, specialized software, and older applications may keep settings or save files in places the tool does not look. You may need to manually copy those files or reconfigure the application on the new Mac. Check the application's documentation or support page if something does not work as expected after migration.

Security-related settings do not always transfer completely. Two-factor authentication codes, app-specific passwords (like those generated for Gmail or Apple ID), and some biometric settings may not move over. You will need to set up two-factor authentication again on the new Mac and generate new app-specific passwords where required. This is intentional — Apple does not transfer these for security reasons.

Virtual machines, bootcamp partitions, and some specialized development tools may require separate handling. If you use virtualization software like Parallels Desktop or run Windows through Boot Camp, check the software's documentation for the proper migration method rather than relying on Migration Assistant alone.

How to check what transferred successfully

After Migration Assistant finishes, spend time exploring your new Mac to confirm everything is where you expect it. Open your Applications folder and verify that the programs you use regularly are there. Check System Settings to see if your preferences transferred — look at Display, Sound, Keyboard, and Trackpad settings to confirm they match your old Mac.

Sign in to your email, social media, and other accounts to verify that your saved passwords work. If a password does not work, it may not have transferred, and you will need to reset it. Open Safari and check that your bookmarks and browsing history are present. If you use iCloud, sign in to your Apple ID and confirm that your photos, documents, and other synced content appear on the new Mac.

Test a few applications to make sure they launch and function normally. Some older applications may have compatibility issues with the new Mac's operating system, even though they transferred successfully. If an application does not work, you may need to update it or find an alternative.

Transferring data that Migration Assistant missed

If you discover that something did not transfer, you have several options. For cloud-based files, simply sign in to your account on the new Mac and the files will sync automatically. For local files that did not transfer, you can copy them manually using an external drive or by connecting the old Mac to the new one again.

For application settings that did not transfer, check whether the application has a preferences or settings file in your old Mac's Library folder. You can copy the entire folder for that application (usually located at ~/Library/Application Support/[App Name]) to the same location on your new Mac. Close the application first, paste the folder, then relaunch the application.

If you need to transfer a large amount of data that did not move over, using an external hard drive is often faster than transferring over the network. Connect the drive to your old Mac, copy the files you need, then connect it to the new Mac and paste them in the correct location.

Running Migration Assistant more than once

You can run Migration Assistant multiple times if you realize you forgot something or want to transfer additional data. Each time you run it, you can choose which user accounts and what types of data to transfer. However, running it multiple times on the same destination Mac can create duplicate files or overwrite settings you have already customized on the new machine.

A safer approach is to transfer everything once, then manually delete anything you do not want afterward. This avoids the risk of overwriting new settings or creating conflicts. If you do run Migration Assistant again, be selective about what you transfer the second time to avoid duplicating data.

Compatibility issues after migration

If your new Mac has a significantly newer operating system than your old one, some older applications may not work even though they transferred successfully. Applications built for Intel Macs may not run on Apple Silicon Macs (M1, M2, M3 chips) unless they have been updated by the developer. Check the App Store or the application's website to see if an updated version is available.

Some applications require re-activation or re-licensing on the new Mac. If you encounter a message saying the application is not licensed or needs to be activated, you may need to enter your license key or sign in to your account again. Keep your license information and product keys accessible during the migration process so you can handle these situations quickly.

Frequently Asked Questions

Will my passwords transfer to the new Mac?

Passwords stored in Keychain transfer, so most website and network passwords will work on the new Mac. However, app-specific passwords (like those for Gmail or Apple ID) and two-factor authentication codes do not transfer. You will need to generate new app-specific passwords and set up two-factor authentication again on the new Mac.

What if I want to transfer only some files, not everything?

Migration Assistant does not have a granular file-selection option during the initial transfer. However, you can transfer everything and then delete what you do not want afterward. Alternatively, you can use an external drive to manually copy only the files you need from your old Mac to the new one.

Can I transfer data from a Mac running an older operating system to one running a newer system?

Yes, Migration Assistant works across different operating system versions. However, some applications designed for older systems may not function properly on newer ones. Check whether your applications are compatible with the new Mac's operating system before or after migration.

Do I need to keep my old Mac connected during the entire migration?

Yes, both Macs need to stay connected and powered on throughout the migration process. If the connection drops, Migration Assistant will pause and you can resume, but keeping both machines connected and awake ensures the transfer completes without interruption. The process can take several hours for large amounts of data.

Will my external hard drives and USB devices transfer their settings?

External drives and USB devices themselves do not transfer — you will need to reconnect them to the new Mac. However, any settings related to those devices (like backup preferences or external drive configurations) may transfer if they are stored in your user library. You may need to reconfigure some external device settings on the new Mac.