How to keep Migration Assistant from overwriting existing files on a new Mac

Glenn Fleishman
31 August, 2017
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The Mac has a great app called Migration Assistant that is very helpful when setting up a new computer and you need to transfer files from an old Mac. Jim O’Reilly asks a great question about using Migration Assistant:

If I use Migration Assistant, how can I avoid writing over on the new Mac files with the same name as the corresponding files from the old Mac?

While Migration Assistant is relatively straightforward to use, it does have settings that let you twiddle what’s transferred.

Typically, after you go through the setup process and connect two Macs, you’re given the option to transfer four kinds of things:

  • Applications
  • User accounts
  • Other files and folders, which covers the Shared folder in the Users folder and folders you created at the top level of a drive
  • Computer & Network Settings

You can also expand user accounts and Computer & Network Settings to de-select particular items as well. In most cases, your best bet is to do the full migration. Although it’s not documented, Migration Assistant doesn’t overwrite new versions of applications with older ones, which may be one of your concerns.

For user accounts, Apple won’t overwrite an account with the same name by default. Migration Assistant prompts you about whether you want to rename the account from the old computer or overwrite the account on the new computer with the files from the old Mac.

Files stored outside user accounts won’t be overwritten, but they could be merged, so a folder might contain a collection of old and new files.

As always, don’t expect everything to go perfectly! Make a full backup of your new computer in case any files you want to retain are unintentionally erased.

One Comment

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  1. Stephen Nicholson says:

    I recently upgraded from a 8yo iMac to a new iMac, doing a full migration during setup. Broadly I was impressed with how well it worked – particularly asking me if I wanted Time Machine to to continue on with my current backup. I had wondered how I’d access my old backups, so that was a pleasant surprise.

    Minor quibbles:
    • my old iMac was updated to macOS 10.12.6, while the new iMac wasn’t – wonder if it would be better if I’d been asked about upgrading prior to migration.
    • migration didn’t bring across my old iWorks apps – have kept them for the Pages mail-merge.
    • could have appreciated a prompt to add the new iMac to the linked devices in iPhone Messages.

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