Stuck with an Update on the wrong drive

[dkjackson]

Here is my story of a self inflicted wound. My PC was booted from the EFI on my Big Sur NVMe, but running Catalina from a SSD. I had not run this drive in a while, so I did some updates. It is a Vanilla Catalina and has run upgrades without trouble. The latest update for Catalina was there and without too much fear, I started the update.

Of course the update for Catalina was setup on the boot drive (Big Sur) and failed because of the OS mismatch. I can boot OC 0.6.7 and run both Catalina and Big Sur, but the Big Sur OS partition is now the update partition.

Is there any way to get the update partition rolled back to the Big Sur OS partition?

 

[Edhawk]

If the way the updates work in Big Sur are the same a they were with earlier versions of macOS, then yes there is a way to stop the update on the Big Sur drive.

First, you would need to boot your system, and select the Catalina icon, not the install macOS on Big Sur icon. i.e. boot into the OS without the update progressing. If possible select the Big Sur icon, again not the installer icon.

Then when at the Catalina Desktop, open the Big Sur-Data partition in a Finder Window, and look to see if there is a folder called 'Data' or something similar on the root of the Big Sur drive. With older versions of macOS this 'Data' folder contained the update/upgrade files, simply deleting it stopped the update process.

However, with the changes Apple have introduced since Catalina things might have changed. The 'Data' folder may be on the protected part of the drive, so it can't be deleted from within Catalina.

You may have to boot into the Big Sur drive, mount the drive in Read/Write mode (use the Hackintool > Utilities tab > Gatekeeper (House) icon for this task) so you are able to delete the 'Data' (or whatever Apple have named the new folder) from the root of the Big Sur-Data drive.

This should hopefully remove the 'install macOS on Big Sur' icon from the OpenCore boot screen or picker list. If not you may need to use the Clean Nvram and/or Reset Nvram using the icons on the OC boot screen/picker list.

This is a screenshot of the 'Big Sur-Data' partition from my system, yours should look the same but hopefully with the additional 'Data' update/upgrade folder present.

Let us know how you get on.

If you can post a screenshot of what you find on the Big Sur-Data partition, so we know what to look for in the future.

 

[dkjackson]

Here is what I understand so far
/System/Volumes/Update
has been mounted as / on the Big Sur Drive and is a system snapshot as Hackintosh HD

If I boot to Catalina (Lifeboat drive) and delete the Update directory on Hackintosh HD will it go back to normal?

 

[Edhawk]

I forgot about the Update partition in Big Sur. I don't think you can delete or remove that partition not without completely messing up the Big Sur drive.

The thing with Big Sur is it takes snapshots, so I am wondering if you can revert back to a snapshot of the drive before the update was applied, using system restore or similar via Recovery Partition. Have a read of this post regarding snapshots - https://eshop.macsales.com/blog/56681-working-with-macos-snapshots/

I would also recommend reading this Ars Technica Big Sur Review - https://arstechnica.com/gadgets/2020/11/macos-11-0-big-sur-the-ars-technica-review/11/

If the Snapshot fix doesn't work, you may need to look to salvage what you can from the Big Sur drive, and once you have saved all your files, folders apps etc. run a clean install of Big Sur on the drive.

 

[dkjackson]

Thanks @Edhawk. I have been running Time Machine, and I took a Carbon Copy drive image to an external drive about 2 weeks ago. I guess we’ll see how well my backup strategy works. I always used to tell people, “unless you’ve restored a backup, you don’t really have one.”

 

[Edhawk]

The CCC clone would be the better/quicker restore option. Boot to the clone and clone the drive back to your normal macOS drive

 

[dkjackson]

I have restored and installed Big Sur several times over the weekend and the result is the same. Once you do an update, you actually boot to a System Snapshot because Apple wants it that way according to the info in the Ars Technica Big Sur Review in the link by @Edhawk. According to the article Apple does it this way from what they learned on iPad.

I still have a ghost MacOS Installer in my OC boot menu and I have no idea where it comes from nor how to get rid of it. My system is stable and I’m back to X-Plane 11.