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User profile for user: Curtis Von Hagt
Curtis Von Hagt Author
User level: Level 1
4 points

Clean install

I Want to make a new clean install on my iMac late 2015 without losing any data at all.

I have a Mac mini which has a copy of Catalina and nearly or all of the applications I’d like to take over to the iMac which has Mojave installed on it but probably only some applications. I have a very good back up system for both machines.

I don’t want to have too much on iCloud even though I’d be willing to upgrade my iCloud Drive data, for the time I need it.

A detailed way of setting it up. Any good tips or a worthwhile walk through article would be most welcome.

thanking you in advance

Curtis

iMac 27″, macOS 10.14

Posted on Jan 26, 2021 12:36 PM

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User profile for user: Jack-19
Jack-19
User level: Level 8
46,002 points

Posted on Jan 27, 2021 2:26 AM

Hi again Curtis Von Hagt,


In this case, you will need to download macOS Catalina using this link and choose Catalina, How to get old versions of macOS - Apple Support, and make a bootable installer for Catalina using an external hard drive or USB Flash drive over 16GB, How to create a bootable installer for macOS - Apple Support.


Just backup your data!


Then, use my revised directions for Catalina:


  1. First, sign out of your Apple ID (System Preferences > Apple ID/iCloud > Sign Out)
  2. Shut down the iMac, and plug in the bootable installer.
  3. Turn on the iMac. When you hear the startup chime or the screen lights up, press and hold the "option" key, and select the bootable installer.
  4. Connect to WiFi in the top right hand corner.
  5. Go to Disk Utility
  6. In the toolbar of Disk Utility, select "View" > "Show All Devices."
  7. Select the main drive name. Typically, this will be at the top of the list. This will be either be "APPLE HDD", "APPLE SSD", or "Fusion Drive".
  8. Click Erase, and input the following exactly: Name: "Macintosh HD" (no quotes in name) Format: "APFS" Scheme "GUID Partition Map."
  9. Click Erase.
  10. Quit Disk Utility
  11. Select Install macOS
  12. Follow the prompts to install Catalina.
  13. Let the process finish. Do not turn off your Mac, restart your Mac, or disconnect from WiFi.
  14. Setup your Mac again, and restore your data.


If you have any questions, you can post back here.


Cheers,


Jack


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Question marked as Top-ranking reply
User profile for user: Jack-19
Jack-19
User level: Level 8
46,002 points

Jan 27, 2021 2:26 AM in response to Curtis Von Hagt

Hi again Curtis Von Hagt,


In this case, you will need to download macOS Catalina using this link and choose Catalina, How to get old versions of macOS - Apple Support, and make a bootable installer for Catalina using an external hard drive or USB Flash drive over 16GB, How to create a bootable installer for macOS - Apple Support.


Just backup your data!


Then, use my revised directions for Catalina:


  1. First, sign out of your Apple ID (System Preferences > Apple ID/iCloud > Sign Out)
  2. Shut down the iMac, and plug in the bootable installer.
  3. Turn on the iMac. When you hear the startup chime or the screen lights up, press and hold the "option" key, and select the bootable installer.
  4. Connect to WiFi in the top right hand corner.
  5. Go to Disk Utility
  6. In the toolbar of Disk Utility, select "View" > "Show All Devices."
  7. Select the main drive name. Typically, this will be at the top of the list. This will be either be "APPLE HDD", "APPLE SSD", or "Fusion Drive".
  8. Click Erase, and input the following exactly: Name: "Macintosh HD" (no quotes in name) Format: "APFS" Scheme "GUID Partition Map."
  9. Click Erase.
  10. Quit Disk Utility
  11. Select Install macOS
  12. Follow the prompts to install Catalina.
  13. Let the process finish. Do not turn off your Mac, restart your Mac, or disconnect from WiFi.
  14. Setup your Mac again, and restore your data.


If you have any questions, you can post back here.


Cheers,


Jack


Reply
User profile for user: Jack-19
Jack-19
User level: Level 8
46,002 points

Jan 26, 2021 1:01 PM in response to Curtis Von Hagt

Hi Curtis Von Hagt,


To make a backup, you can use an external hard drive to "copy and paste" data over, you can use iCloud as you mentioned. For a true clean install, do not use Time Machine.


When you are ready to clean install (I'm guessing Big Sur), use the Instructions Below. This WILL erase ALL Data!


  1. First, sign out of your Apple ID (System Preferences > Apple ID/iCloud > Sign Out)
  2. Restart the iMac
  3. When you hear the startup chime or the screen lights up, press and hold Option + Command + R. This will load Big Sur Recovery.
  4. Connect to WiFi in the top right hand corner. Confirm you are in Big Sur Recovery by the description containing "Big Sur" on the "Reinstall macOS" app.
  5. Go to Disk Utility
  6. In the toolbar of Disk Utility, select "View" > "Show All Devices."
  7. Select the top drive name. This may be "APPLE HDD", "APPLE SSD", or "Fusion Drive".
  8. Click Erase, and input the following exactly: Name: "Macintosh HD" (no quotes in name) Format: "APFS" Scheme "GUID Partition Map."
  9. Click Erase.
  10. Quit Disk Utility
  11. Select Install macOS
  12. Follow the prompts to install Big Sur.
  13. Let the process finish. Do not turn off your Mac, restart your Mac, or disconnect from WiFi.
  14. Setup your Mac again, and restore your data.


If you have any questions, you can post back here.


Cheers,


Jack

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User profile for user: rkaufmann87
rkaufmann87
User level: Level 10
143,320 points

Jan 26, 2021 1:03 PM in response to Curtis Von Hagt

Curtis,


You need to have a backup, such as a Time Machine or Bootable clone backup before you take any steps. This preserves your data.


You cannot migrate from a newer version of Mac OS to an older version, for example cannot backup Catalina and restore to Mojave. You can manually restore data but not apps.


Why do you feel it is necessary to do a clean install? In most cases this is a waste of time and effort if you are experiencing a problem.

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User profile for user: Curtis Von Hagt
Curtis Von Hagt Author
User level: Level 1
4 points

Jan 26, 2021 11:11 PM in response to Jack-19

Hi Jack thanks for the reply. I want to install. Catalina. I do a lot of work with Pro Tools. And at the moment it’s not recommended to use Big Sur cause it ain’t compatible and that’s The reason why I already installed Catalina on my Mac mini. Getting it ready for the transfer.

the Mac mini has nearly all the applications I need and it works well too.

the reason to make a clean install is. My Mac mini uses about 80 Gigabyte and my iMac which has nearly the same programmes are taking up around 140 Gigabyte.

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User profile for user: Curtis Von Hagt
Curtis Von Hagt Author
User level: Level 1
4 points

Jan 26, 2021 11:16 PM in response to rkaufmann87

Hi There thanks for the reply. I want to install. Catalina. I do a lot of work with Pro Tools. And at the moment it’s not recommended to use Big Sur cause it ain’t compatible and that’s The reason why I already installed Catalina on my Mac mini. Getting it ready for the transfer.

the Mac mini has nearly all the applications I need and it works well too.

the reason to make a clean install is.

My Mac mini uses about 80 Gigabyte and my iMac which has nearly the same programmes are taking up around 140 Gigabyte.

The reason for a clean install of Catalina and not to Big Sur

Thanks


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User profile for user: Curtis Von Hagt
Curtis Von Hagt Author
User level: Level 1
4 points

Jan 27, 2021 4:37 AM in response to Curtis Von Hagt

Thanks Jack for confirming. Just a couple a more questions.

I’d like to use the same account name data an such, as my other machine! (That’s important and the following too) And import my applications Too. Should I use the the time machine backup from the other machine or connect over a thunderbolt connection.

Thanks for your valuable time n info.

Curtis.

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Clean install

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