How do I downgrade my Mac OS X operating system

Last Modified: Feb 22, 2011 5:41 PM
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Downgrading the operating system is not easy.

With 10.5.1 Intel or later (including 10.6 or later) to 10.5:

1. Verify you made a Time Machine backup before you upgraded to 10.5.1 or later.
2. Boot off the Leopard installer disk.
3. Select the installation language.
4. Go to the Utilities menu and use the Restore from Time Machine backup to restore to your Time Machine state before you installed 10.5.1.

This will only work, if you have no data to salvage from 10.5.1 or later.

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With:

10.6 or later
From   (10.5 Intel through 10.5.8)        to   (10.4.4 through 10.4.11)
From   (10.5 PowerPC through 10.5.8)  to   (10.0 through 10.4.11)
From   (10.4 through 10.4.11)   to   10.3
From   (10.3 through 10.3.9)     to   10.2
From   (10.2 through 10.2.8)     to   10.1

Either restore from your backup or:

1. Backup your existing data by cloning it to external hard drive(s) at least twice.

2. Write down registration codes for installing applications.

3. Erase and install the operating system with none of the backups connected to the machine during the erase and install process, and no peripherals other than display, keyboard and mouse attached.

4. Restore user documents that are capable of being downgraded.
Ask on Discussions if the applications you use can be downgraded before attempting this.

5. Install from the original installation disks which shipped with your machine additional applications which didn't ship with the operating system:

http://docs.info.apple.com/article.html?artnum=61802

6. Install from the third party CDs and downloads any other applications.

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Finally, users downgrading from 10.3.x to another 10.3.x, and 10.2.x to another earlier 10.2.x can use archive and install:

http://docs.info.apple.com/article.html?artnum=107120

Note:

1. Apple applications left behind from a newer installation may not work in an older installation on an archive and install.

2. Installation from restore disks are required if your Mac is

- - Intel and shipped with 10.4.4 through 10.4.11.
- - The install you are attempting is the minimum that Mac can run: http://docs.info.apple.com/article.html?artnum=25517
- - The retail installation available is older than the Mac itself.

This is the 2nd version of this tip. It was submitted on May 12, 2010 by a brody.
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