I have a Catalina mac which is not compatible with the latest Macosx. Do I have to erase Macintosh HD to clean install Catalina or will it suffice to reinstall the Catalina from USB pendrive??

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I have a Catalina mac which is not compatible with the latest Macosx. Do I have to erase Macintosh HD to clean install Catalina or will it suffice to reinstall the Catalina from USB pendrive??

I have a Catalina on mac which is not compatible with the latest Macosx. Do I have to erase Macintosh HD to clean-install Catalina or will it suffice to reinstall the Catalina from USB pendrive??

Is there any other, simpler method to install Catalina from scratch on the Mac? I simply want to install it anew without applications and settings in order to make it work faster and without errors which have accumulated for years.

Mac mini, macOS 10.15

Posted on Dec 5, 2020 8:37 AM

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Answer 1

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John Galt

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Dec 5, 2020 8:58 AM in response to bogmarcin

Follow all the instructions in What to do before you sell, give away, or trade in your Mac, including the most important one which is to create a Time Machine backup: Back up your files with Time Machine on Mac.

Step 7 alludes to a "setup assistant" which will ask if you want to transfer content from a Time Machine backup. Since you are not transferring ownership of that Mac, proceed with it. You may choose among broad categories of items to transfer. Leave your User Account selected, but de-select all other options.

That will accomplish what you seek.

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Answer 2

John Galt

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146,510 points

Dec 5, 2020 10:42 AM in response to bogmarcin

I can't be certain. Apple changed their reinstall macOS instructions literally a day or two ago, and whatever Mini model you have I probably do not have one to confirm them.

Refer to the How to reinstall macOS instructions referenced in Step 7, but it really doesn't matter. The reason is that as long as you have that Time Machine backup, you will be able to reinstall any macOS version that remains available. The worst possible outcome is that you would need to restore that entire backup, and you'll be back to the beginning.

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Answer 3

John Galt

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Dec 7, 2020 3:15 AM in response to bogmarcin

There were some macOS versions that required an intermediate step before you could upgrade macOS to the latest version. Off the top of my head I believe it was anything earlier than El Capitan had to be upgraded to El Cap first, after which you could upgrade directly to the latest version. The "Other macOS installation options" explained in How to reinstall macOS allude to them, but it's unclear to me whether the USB installer would obviate that requirement.

These three startup key chords are described in How to reinstall macOS:

⌘ R to reinstall the same macOS version

⌥ ⌘ R to upgrade to the latest macOS version

⇧ ⌥ ⌘ R to reinstall that Mac's originally installed macOS version

Conditions apply to each one which makes it a bit more complicated than that.

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Answer 4

bogmarcin Author

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Dec 7, 2020 2:17 AM in response to John Galt

I have once ended up in the OSX my Mac came with (can't remember if in the identical situation), after which to get to the newest then system version, I had to install some intermediate ver. because it was not possible to make such a big jump in the development of Mac OSX. Hence I wonder if you could advice me on whether using USB installer with the Catalina would prevent such additional complications.

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Answer 5

bogmarcin Author

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Dec 8, 2020 12:42 AM in response to John Galt

The reinstallation went rather smoothly but I can’t proceed with migration assistant. Does it have something to do with the fact that I have changed the password to my Apple ID just before the installation?. Currently I do have up and running mac logged-in with Apple ID, and with all set, but when I launch the migration assistant, it does nothing after clicking on continue button and selecting my time machine disk , strictly speaking it accepts the selected disk but I wait infinitely long for the next step and give up.

Also there’s another problem - I can't resize windows

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