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Clean install of macOS Catalina

Can I clean install macOS Catalina, i.e. reinstall from macOS recovery, without losing any existing applications or files? If so what is the correct procedure?

iMac 21.5″, macOS 10.15

Posted on Aug 13, 2020 6:05 AM

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Posted on Aug 13, 2020 6:18 AM

No, by definition a clean install means no apps, data, settings, etc - it will be as though you got a new Mac. The procedure is to:

  1. Back up your data. Either use Time Machine, or something like SuperDuper or Carbon Copy Cloner.
  2. Reinstall Catalina. A proper clean install means you'd create a bootable installer disk and install from there, erasing your HD in the process.
  3. Restore your data. This process would vary depending on the method you used to back up in step 1.


Check out OSXDaily's walkthrough for more info.

3 replies
Question marked as Top-ranking reply

Aug 13, 2020 6:18 AM in response to KacyAstro

No, by definition a clean install means no apps, data, settings, etc - it will be as though you got a new Mac. The procedure is to:

  1. Back up your data. Either use Time Machine, or something like SuperDuper or Carbon Copy Cloner.
  2. Reinstall Catalina. A proper clean install means you'd create a bootable installer disk and install from there, erasing your HD in the process.
  3. Restore your data. This process would vary depending on the method you used to back up in step 1.


Check out OSXDaily's walkthrough for more info.

Aug 13, 2020 12:17 PM in response to Simon Abrams

Okay thanks Simon. After upgrading to Catalina I've been experiencing persistent issues, such as endless beachballs and apps including Safari taking a long time to launch, or that quit unexpectedly. So I'm thinking I may have corrupt files within the operating system which have been compounded by updates since the as supplied 2016 Sierra version. The latest Catalina version 10.15.6 on my mac has nearly killed it. At least now I know what I'm in for if I go ahead with a re-install!

Clean install of macOS Catalina

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