utmapp
run macOS 26 via macOS 15.5?
Hi
Not sure if this is feasible, but it would be nice to run a beta of Tahoe off of 15.5
Ive tried using the IPSW, and i get a Install Prompt
Clicking Yes gets me (eventually)
and
No, but I did find out that it works if you install 15.5, enable beta updates, and then do an update to 26 (im in the process as we speak)
If it's the same as previous releases, you need the latest Xcode beta to install the beta IPSW
Anyone had any luck signing into iCloud / App Store, installing guest support tools, or accessing a shared folder?
I installed Xcode 26 on 15.5, then installed macOS 26 on UTM (4.6.5 (108)) with no issues during installation. However, post installation, I'm unable to sign into the Apple ID that I use for development (it doesn't send a code to my devices unless specifically retried, then presents an error after the code is entered), shared folders do not appear in the guest OS, and when attempting to install the guest support tools no USB storage device ever shows up in the guest OS, either.
Update: Shared folder showed up after VM shutdown and restart.
Im able to sign into iCloud, access shared drives
im not able to use Apple Intelligence features from within the VM which is unfortunate though. a quick check from Xcode within the host and I can't enumerate the neural engine
Apple Intelligence Pref pane is also not showing up with the intelligence options, just Siri, which makes it seem like the VM engine doesn't pass the neural engine through?
You need this package from Apple Developer website:
I'd be led to believe that the dialog is prompting to install these tools, but failing to do so, is that not the case?
You need this package from Apple Developer website:
I'd be led to believe that the dialog is prompting to install these tools, but failing to do so, is that not the case?
It fails because it is a beta tool. It has to be installed manually and then everything works without the need to install Xcode.
I'm not sure what that means... what is the dialog prompting you for, if not to install the tools?
it means the install doesnt work - as the install isnt going to find beta tooling, only release tooling. the only tooling to enable this is beta tooling, therefore the automated ability to find the required components fail. Thus you have to manually install them.
You need this package from Apple Developer website:
This is the solution. Once I installed the package starting the new VM + installation happened without errors. No Beta XCode required nor upgrading from a 15.5 VM.
Getting the below error after having installed the device support package and restarted (twice). No errors / dialog boxes regarding the software update - I get the initial "Would you like to install macOS?" box, then it thinks a bit and spits out the non-specific error. Anyone else get this?
I don't think this should be closed, how is a new user supposed to know that you need to install that specific package from Apple? The dialogs appear to be offering the solution, but they fail, and I'm still not sure what it's attempting to do. Is there any situation where the "software update" dialog will succeed?
I think of it this way, the use of beta software is in general "uncharted waters" and is something that most users will not participate in. The framework doesn't return any details beyond a generic failure so if we override that message with something specific, it may end up confusing users who hit the generic error for other reasons. A feedback request to Apple to return a better error message and not the generic error when this is hit would be an option.
OK - so for macOS B3 and UTM you need install
Device Support for macOS 26 beta 2
Mobile Device Support 1950A4
It's about 2/3rds down the software install page
It should then work (I assume you also loaded the latest xcode B3 etc).
This works for me so if someone else can confirm then we can close the thread as solved !
the use of beta software is in general "uncharted waters" and is something that most users will not participate in.
So you anticipate that this is a problem on Apple's side that will be resolved by the time their software is stable?
This is resolved by installing the right package from Apple
I clearly stated that I installed the device support package, which I downloaded from the same page as the IPSW. If I still received the error, it was obviously not resolved.
If you already have macOS 15 VM you can update it to 26 beta, I tried and it worked.
Run this in VM and then update from Settings. No need to do anything else.
sudo defaults write com.apple.MobileAsset MobileAssetAssetAudience -string 832afda4-7283-41da-a95b-75f4a151e473
sudo defaults write com.apple.MobileAsset MobileAssetServerURL-com.apple.MobileAsset.SoftwareUpdate -string "https://swscan.apple.com/content/catalogs/others/index-26seed-26-15-14-13-12-10.16-10.15-10.14-10.13-10.12-10.11-10.10-10.9-mountainlion-lion-snowleopard-leopard.merged-1.sucatalog.gz"
sudo killall -HUP mobileassetd
sudo killall -HUP betaenrollmentd
open "x-apple.systempreferences:com.apple.Software-Update-Settings.extension"
source: https://github.com/insidegui/VirtualBuddy/discussions/194#discussioncomment-13558615
for anyone else arriving here:
Device Support for macOS 26 beta 2
from
https://developer.apple.com/download/os/
is the approach that worked for me to install :
macOS 26 Released September 15, 2025 Build 25A354
on top of macOS 15.7 with UTM Version 4.6.5 (108)
