Software Update to install Tahoe 26.7 fails on a blank screen

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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.
 
Can confirm. I feared that it was perhaps related to me updating my host OS to 27. But given this thread, I suspect it's a Parallels bug.
 
JeffA14 said:
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.
Click to expand...
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.
 
I've been in contact with Parallels support about this and it is getting escalated to the engineering team. There is nothing as users we can do about this, and I've tried various installation methods without success.
The fault is ultimately with Apple and the Apple Hypervisor Framework so all virtualisation solutions are affected.

It is definitely worth us all reporting this to Parallels support so that they know that there are many users looking for a fix. Ultimately Parallels and Apple are known to work together, however Apple without Parallels input are likely to ignore this and tell us to upgrade our guests to macOS 27, which we all have our reasons for not doing.
 
For what it's worth, I've noticed the same behavior with UTM and also VirtualBuddy. That is, going from 26.6.2 to 26.7 results in a black screen partway through. Hard powering-off the VM and powering it back on again results in it still being on 26.6.2.

So perhaps this isn't necessarily a Parallels bug, but rather a bug in the underlying virtualization framework that all three products use.
 
Macintosh Rescue said:
I've been in contact with Parallels support about this and it is getting escalated to the engineering team. There is nothing as users we can do about this, and I've tried various installation methods without success.
The fault is ultimately with Apple and the Apple Hypervisor Framework so all virtualisation solutions are affected.

It is definitely worth us all reporting this to Parallels support so that they know that there are many users looking for a fix. Ultimately Parallels and Apple are known to work together, however Apple without Parallels input are likely to ignore this and tell us to upgrade our guests to macOS 27, which we all have our reasons for not doing.
Click to expand...
yea, most people should avoid the early versions of new OSes as they are always buggy, hence why I want the latest version of the second-newest version.
 
I just confirmed the same issue, but it is not restricted to just Parallels Desktop. I also use an app called VMTek available from the Mac App Store and the same problem happens with VMs used with that app as well. So it appears this to be an Apple / OS issue.
 
I have tried to install multiple updates 26.5.2 > 26.6.2, 26.6.2 > 26.7 and I am receiving a black/blank screen every time. I wiped it out and installed a brand new MacOS VM using the Parallels download which is now 26.6.2 and the same thing happens when I try to go to 26.7 or even 27.0. Every time it just gets stuck on an empty black screen with nothing in it, and nothing happens. When I try to reboot or even have to force stop or shutdown it reverts back to the original installed version. I tried deleting /Library/Preferences/Parallels and rebooting and that does not fix it.
 
I can confirm that the final public release of macOS 26.7.1 is still affected.

I have an existing macOS 26.6.2 VM that has repeatedly failed to update to 26.7 under Parallels Desktop 27.0.1. The update starts normally, but eventually the VM reaches a blank screen and never completes. If I Stop the VM and restart it, it boots normally back into 26.6.2.

I previously reproduced the problem on two different Macs and also retested after upgrading Parallels Desktop to 27.0.2, with the same result.

This morning I tried updating the 26.6.2 VM directly to the final public release of macOS 26.7.1. Unfortunately, the behavior is unchanged: the update ends at the same blank screen and does not complete.

So, at least in my testing:

26.6.2 → 26.7: fails
26.6.2 → final 26.7.1: fails
 
So, interestingly I was curious about whether 26.7.1 would solve the problem, and...
I forgot that I had a VM running the update process (from 26.6.2).

Interestingly, I got on to my computer this morning and my VM was sitting at at 26.7.1. And is seemingly responsive. My host is also 27.0.1

So, for anybody having this problem, maybe try letting the update process run overnight?
 
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