User profile for user: erkki967
erkki967 Author
User level: Level 1
13 points

After update to macOS Sequoia 15.3.1, dual boot with Monterey failed

I have Intel Mac Mini 2018 where I have dual boot Sequoia / Monterey. Dual boot has been fine until I installed the Sequoia 15.3.1 update. At first I saw that now there is a problem when in system settings the boot system selector showed that I have two Monterey disks as options. One booted to Sequoia, the other to nothing: the boot ended when the progress bar was about 50%.


Then using system recovery I reinstalled macOS Sequoia. Then I had no option to select another os, but the APFS partition was there and using Finder I could see the Monterey files. Then I reinstalled Monterey using a bootable usb disk, but the install ended at phase when Monterey was to be opened (same 50% as above). Then I and recovered the Monterey contents from my CCC backup disk. Now I have two options to select the boot system, but only Sequoia boots.


What could be done? I have several apps to maintain for also Intel surroundings, and most of them can be updated in Xcode / Sequoia having target to Monterey. Monterey os in development mac is necessary for NavigationView which is deprecated in Sequoia, and Monterey os in user's mac does not accept NavigationSplitView which is the similar control for Sequoia.



Mac mini, macOS 15.3

Posted on Mar 10, 2025 12:17 PM

Reply
2 replies
Sort By: 
User profile for user: leroydouglas
leroydouglas
Community+ 2025
User level: Level 10
192,192 points

Mar 10, 2025 6:55 PM in response to erkki967

erkki967 wrote:

I have Intel Mac Mini 2018 where I have dual boot Sequoia / Monterey. Dual boot has been fine until I installed the Sequoia 15.3.1 update. At first I saw that now there is a problem when in system settings the boot system selector showed that I have two Monterey disks as options. One booted to Sequoia, the other to nothing: the boot ended when the progress bar was about 50%.

Then using system recovery I reinstalled macOS Sequoia. Then I had no option to select another os, but the APFS partition was there and using Finder I could see the Monterey files. Then I reinstalled Monterey using a bootable usb disk, but the install ended at phase when Monterey was to be opened (same 50% as above). Then I and recovered the Monterey contents from my CCC backup disk. Now I have two options to select the boot system, but only Sequoia boots.


See if there is anything here—

Install macOS on an external storage device and use it as a startup disk - Apple Support


Add, delete, or erase APFS volumes in Disk Utility on Mac



Reply
User profile for user: erkki967
erkki967 Author
User level: Level 1
13 points

Mar 29, 2025 10:16 AM in response to erkki967

I finally solved this problem. I made a new bootable Monterey install usb stick using a brand new Kingston memory stick. And now I have a dual boot Mac Sequoia / Monterey. Now I must remember not to update Sequoia in this Mac, because it is possible that the dual boot ruins again. Then I tried to make an external bootable macOS Monterey ssd with Samsung 850 EVO. I was very careful in every step, but the install ended to a yellow triangle and error text without explanation.


So you should use only new memory devices for this kind of operations. Samsung 850 was bought 10 years ago and been in use in Windows PC.


I noticed that using Xcode in Sequoia with target to Monterey does not end to good results in all app details. My customer noticed at once that some colors were missing in some views. Today I saw with Xcode in Monterey that the colors were just like they should.

Reply

After update to macOS Sequoia 15.3.1, dual boot with Monterey failed

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.
Learn more Sign up