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Rollback to Catalina from Big Sur without having to do a clean install

Searching for new instructions, would like to rollback to Catalina from Big Sur without having to do a fresh install, is this possible? Lots of issues with Big Sur (loss of many calendar features).


All of my files are backed up to google drive just want to avoid re-setting system preferences and re-downloading files again.

MacBook Pro 15″, macOS 10.15

Posted on Feb 21, 2021 11:50 AM

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Posted on Feb 21, 2021 12:48 PM

Unless you want to keep Big Sur and have sufficient storage to create a new logical partition adjacent to it for a Catalina installation, you must wipe the Big Sur installation as part of the roll back procedure, as one cannot just install Catalina over Big Sur.


The ideal tool for this is Time Machine, which after booting into Recovery, you request that it Restore from a Time Machine backup — provided you made a Time Machine backup of Catalina before upgrading to Big Sur. Under those conditions, the restore from Time Machine would remove Big Sur and repave the partition with Catalina exactly as it was from the last Time Machine backup, including all of your user data and configuration settings.


Without a Time Machine backup of Catalina, a rollback from Big Sur means wiping the drive, installing Catalina, and then restoring from Google Drive. That is not supported by Apple and if Google Drive changes any of the access control settings or other extended attributes on what you backed up, your Catalina installation will be frought with risk and potentially things that don't work.

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Question marked as Top-ranking reply

Feb 21, 2021 12:48 PM in response to TrinityStudent2011

Unless you want to keep Big Sur and have sufficient storage to create a new logical partition adjacent to it for a Catalina installation, you must wipe the Big Sur installation as part of the roll back procedure, as one cannot just install Catalina over Big Sur.


The ideal tool for this is Time Machine, which after booting into Recovery, you request that it Restore from a Time Machine backup — provided you made a Time Machine backup of Catalina before upgrading to Big Sur. Under those conditions, the restore from Time Machine would remove Big Sur and repave the partition with Catalina exactly as it was from the last Time Machine backup, including all of your user data and configuration settings.


Without a Time Machine backup of Catalina, a rollback from Big Sur means wiping the drive, installing Catalina, and then restoring from Google Drive. That is not supported by Apple and if Google Drive changes any of the access control settings or other extended attributes on what you backed up, your Catalina installation will be frought with risk and potentially things that don't work.

Feb 21, 2021 12:26 PM in response to TrinityStudent2011

https://support.apple.com/guide/disk-utility/add-erase-or-delete-apfs-volumes-dskua9e6a110/20.0/mac/11.0


If you add a partition and give yourself enough space to reinstall the older system on your Mac, you should be able to create a place to use internet recovery to install the older system or clone back your backup you made before upgrading.


Always backup your data before upgrading or downgrading.

And consider using http://bombich.com Carbon Copy Cloner for exact replicas to external hard drives.

Rollback to Catalina from Big Sur without having to do a clean install

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