How do I set up Sync after migrating, cloning, or restoring a computer?

Setting up a new computer with a migration or disk cloning tool, such as Windows PC transfer, Apple’s Migration Assistant, or Time Machine, copies the Sync desktop app across with your documents. The copy carries the old computer’s identity and its record of what you had, which puts it in conflict with your account. That can produce duplicate files and folders, files that reappear after being deleted, or unexpected deletions.

This article explains what goes wrong, how to avoid it, and what to do if it has already happened.

 

In this article:

Why does this cause problems?

The Sync desktop app stores a local database and a device identity alongside your files. Migration and cloning tools copy both, which leaves the new computer claiming to be the old one.

Depending on what the copied app finds when it opens, you may see one of three outcomes:

  • Duplicates, or deleted files coming back. The copied database disagrees with your account about what should exist.
  • The app reports "In sync" when it is not. Two devices sharing one identity causes the app to believe it has already checked a folder it has not. Files appear in the list but cannot be opened.
  • File deletions. If the local Sync folder has not finished rebuilding, the app can interpret the missing files as deletions you made, and remove them from your account and from every other connected computer.

Which tools are affected?

Any tool that copies an installed application and its data, including:

  • Apple Migration Assistant
  • Time Machine restores
  • Disk cloning and drive imaging tools
  • Windows PC transfer and migration utilities
  • Restoring a computer from a full system image

Copying only your documents to a new computer is fine. The problem comes from copying the Sync app itself.

What should I do before migrating?

Follow these steps on the old computer before you start.

  1. Open the Sync desktop app and let it finish syncing. Wait until the status shows In Sync.
  2. Sign in to the web panel and confirm your recent files are there. The web panel shows what is actually in your account.
  3. Quit the Sync desktop app completely. Closing the window is not enough.
  4. If your migration tool lets you choose what to copy, exclude the Sync application and your Sync folder. You will download your files fresh from the cloud instead.

Note: Do not open the Sync app on the new computer until you have completed the setup below.

Setting up Sync on the new computer

Do not open the migrated copy of the app. Remove it first, then install a fresh copy.

On Windows

  1. If the Sync app opened automatically, quit it from the system tray.
  2. Download and run the Windows uninstaller.
  3. Rename your existing Sync folder to Sync.old.
  4. Install the latest app from the Sync downloads page.
  5. Sign in and let Sync create a new, empty Sync folder.
  6. Allow it to download your files, and wait for the status to show In Sync.

On macOS

  1. If the Sync app opened automatically, quit it. Use Force Quit if necessary.
  2. Download and run the macOS uninstaller.
  3. In Finder, find your existing local Sync folder and rename it to Sync.old. This keeps a local copy and prevents the new installation from colliding with it.
  4. Install the latest app from the Sync downloads page.
  5. Sign in and let Sync create a new, empty Sync folder.
  6. Allow it to download your files from the cloud, and wait for the status to show In Sync.

If setup offers to restore an existing Sync folder

You may see a warning that reads "Proceed only if this is your correct Sync folder." After a migration or clone, choose not to reuse the existing folder. Rename it to Sync.old and let Sync create a new one.

If you prefer to re-use the existing Sync folder and avoid re-downloading all of your files, see the following help article: Moving the Sync folder to a new computer

Once the new folder has finished downloading

  1. Compare Sync.old against your new Sync folder.
  2. Copy across anything genuinely missing, such as files that never finished uploading from the old computer.
  3. Only then delete Sync.old.

Never place Sync.old inside your new Sync folder. It will upload a duplicate copy of everything.

What should I do with the old computer?

If you migrated from an old computer, it will still have the Sync app installed along with a full local copy of your files. Once the new computer has been set up using the steps above and shows In Sync, the old computer can either have Sync removed or carry on being used.

Note: Wait until the new computer has finished downloading and you have confirmed your files are there. Until then, the old computer is a useful backup.

If Sync is no longer needed on the old computer:

  1. Quit the Sync app completely. Closing the window is not enough.
  2. Run the full uninstaller: macOS or Windows.
  3. Only then delete the old Sync folder, or erase the drive.

Note: Do not drag the Sync folder to the trash while the app is still installed and signed in. Deleting files from your Sync folder removes them from your account and from every other computer connected to it.

Rejoining shared folders afterwards

A migration incident can also make your account leave team shared folders you were a member of.

Restoring deleted files does not restore shared folder membership. The two are separate, and a shared folder you have left will not come back with your files.

Once your own files have finished syncing:

  1. Check the Shares tab in the web panel for folders you are no longer in.
  2. Delete or move any old, detached copies of those folders out of your Sync folder first. Leaving them in place causes conflicts when you rejoin.
  3. Rejoin each share, or ask the folder's owner to re-invite you.
  4. Let each folder download cleanly.

When to contact Support

Contact Support if:

  • You notice duplicate files or folders
  • The app reports In Sync but your files cannot be opened
  • You are missing shared folders after a migration
  • A large number of files were deleted from your account

Tell us what tool you used, when it happened, and whether your apps are currently open or closed. If files were deleted, the time range matters most.

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