Software Update to install Tahoe 26.7 fails on a blank screen

OscarA11

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Mac Studio M3 Ultra (MacOs Tahoe 26.7)

Parallels 27.0.1

I install a brand new MacOS VM using Parallels (it only offers 26.6.2) using default settings in Parallel for the VM. It works, I can login etc. Then I go to settings in the VM to download the actual latest Tahoe version 26.7 (like the host machine), and it starts the process, even shows the black screen with the apple logo with a progress bar etc, but then just gets stuck on an empty black screen with nothing in it, and nothing happens for hours. I then reboot, and its still on 26.6.2.
 
I can confirm this, attempting to update (guest VMs) to 26.7 from any prior 26.x release fails (ARM, Mac Studio M2 Max host running 26.7). black screen during update reboot, requires hard power off. This also happens with VirtualBuddy (another virtualization product), so it appears to be an Apple issue. Strangely, had no issues updating 26.7 RC 3, the build just before the general 26.7 release, so something changed in the final 26.7 build. Physical machines have no issues, this only happens in guest VMs.
 
I'm having this issue also: but interestingly the same issue is present with UTM so this is an Apple Hypervisor issue. Hopefully Parallels can chase this up with Apple so in the meantime we should submit support requests through Parallels.
I think I'll try finding a macOS 26.7 IPSW and see if we can at least install a new VM and migrate.
 
The update has caused everything to take more CPU. By increasing the number of cores allocated to my macOS VM I am able to make it through the login process, but everything is molasses. Activity Monitor is showing every running application taking significant CPU just to launch (Terminal taking 114%?). The System, User, and Idle percentages are all displaying as NaN, and the thread count is 0.

Something in this update does not play well with virtualization.
 
The update has caused everything to take more CPU. By increasing the number of cores allocated to my macOS VM I am able to make it through the login process, but everything is molasses. Activity Monitor is showing every running application taking significant CPU just to launch (Terminal taking 114%?). The System, User, and Idle percentages are all displaying as NaN, and the thread count is 0.

Something in this update does not play well with virtualization.
Interestingly, macOS 27 Golden Gate runs very well as a guest OS. It seems to be just an issue with macOS 26 Tahoe (though that also used to work faster).
 
Ah, interesting about it being slow for you. In my case, I started with 26.6.2 and attempted to update to 26.7. After it sitting at the black screen for what seemed like forever, I power cycled the VM. When it came back up, it was unusably slow, but still at 26.6.2. Reverting back to the snapshot brings it back to 26.6.2 but fast.
 
Same here with Parallels Desktop 27.0.2 (58673).
Host: macOS Tahoe 26.7
Guest: macOS Tahoe 26.6.2 → 26.7

The behavior is exactly the same as described above: after the Apple logo and progress bar, the VM ends up on a completely black screen. After resetting/rebooting the VM, it comes back as 26.6.2.
I have reproduced this three times.
 
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