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User profile for user: MisterWooley
MisterWooley Author
User level: Level 1
7 points

How to downgrade to Catalina 10.15.5

Catalina 10.15.6 fatally broke my VirtualBox setup. Unpredictable and random crashing. I am lead to believe that the cause is a kernel memory leak (source VirtualBox & VmWare forum postings).

I want to downgrade to Catalina 10.15.5 which was working fine.

According to Apple support I have to erase my system, install a new copy of Mojave followed by Catalina 10.15.5

The last part of that does not work. Catalina 10.15.5 from the App Store Catalina page 10.15 first but 10.15 is not on the App Store.

Apple support helpfully pointed out that Big Sur will be out soon that Big Sur will not run on my iMac (according to pre release documentation)

Can anyone advise me how to get Catalina 10.15.5 installed.


For clarity I do not want 10.15.6 the current release.

iMac 21.5″, macOS 10.14

Posted on Aug 8, 2020 3:02 PM

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User profile for user: Barney-15E
Barney-15E
User level: Level 10
116,182 points

Posted on Aug 8, 2020 3:36 PM

Unless you already have a Catalina Installer which was 10.15.5, or earlier, you cannot downgrade to 10.15.5. The only version of Catalina that Apple provides as an installer is always the most current version of the OS.

What you downloaded was an update to 10.15.5. You have to have a previous version of Catalina installer in order for the update to work.


Do you have a backup with 10.15.5? If so, you can restore that.

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User profile for user: Barney-15E
Barney-15E
User level: Level 10
116,182 points

Aug 8, 2020 3:36 PM in response to MisterWooley

Unless you already have a Catalina Installer which was 10.15.5, or earlier, you cannot downgrade to 10.15.5. The only version of Catalina that Apple provides as an installer is always the most current version of the OS.

What you downloaded was an update to 10.15.5. You have to have a previous version of Catalina installer in order for the update to work.


Do you have a backup with 10.15.5? If so, you can restore that.

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User profile for user: John Galt
John Galt
User level: Level 10
146,138 points

Aug 8, 2020 4:30 PM in response to MisterWooley

Restore a Time Machine local snapshot: Restore your Mac from a backup - Apple Support. An additional Local Snapshot is always created immediately prior to installing a macOS update.


Otherwise wait for Oracle to update their software.


According to Apple support I have to erase my system, install a new copy of Mojave followed by Catalina 10.15.5


That's not correct anyway.

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How to downgrade to Catalina 10.15.5

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