Stacks are freezing and forcing a reboot since upgrading to macOS27.

Since this started immediately after the macOS 27 upgrade, I would first check Apple menu > About This Mac and confirm which version you are running. 

Apple currently lists macOS 27.0.1, released September 28, 2026. Apple: Apple security releases

The next time the Stack freezes, I would try restarting the Dock before logging out:

Terminal command  is case sensitive killall Dock

The Dock should disappear briefly and come back. 

If the frozen Stack is still there, try: Terminal command  killall Finder

Apple documents relaunching Finder when it becomes unresponsive. Apple: How to force an app to quit on Mac

If neither command clears the floating window, open Activity Monitor >> View All Processes, while the problem is happening. 

You can use it to examine processes, force-quit an unresponsive process, and create diagnostic reports such as Sample Process and Spindump. 

A report captured during the freeze could also be useful with the Apple Feedback report you have already submitted. Apple: Activity Monitor User Guide

I would try reproducing the problem in Safe Mode.

On your M1 Pro Mac, shut it down, hold the power button until the startup options appear, select the startup disk, hold Shift, and choose Continue in Safe Mode.

Then use the Stack normally and see whether the problem occurs.

If the behaviour changes in Safe Mode, I would look at login items and extensions next.

I would not delete Finder, Dock, or Stack preference files yet, because there is not enough evidence to identify any of them as the cause.

If the Mac eventually becomes completely unresponsive and none of these steps helps, restart normally if possible. 

If it will not  restart normally, use Apple's forced-shutdown procedure as a last resort. Apple: How to force an app to quit on Mac

The fact that the keyboard also becomes unresponsive is an important detail. If Terminal and other apps are not  accepting keyboard input, then killall Dock or killall Finder obviously would not help at that point because you can not enter the command.

If Terminal is still usable the next time it happens, I would try killall Dock first, since Stacks are part of the Dock. If Finder itself appears to be what is s hung, killall 

Finder is another option. Neither is guaranteed to fix this particular freeze, but they are reasonable things to try before logging out.

If you can not use Terminal, try Command–Option–Escape. If the Force Quit window comes up and responds, select Finder and choose Relaunch. (Apple Support)

If that doesn't respond either and the Mac won't restart normally, Apple recommends holding the Touch ID/power button until the Mac shuts down. (Apple Support)

Since this started immediately after upgrading to macOS 27 and you've been able to reproduce it repeatedly, I'd make sure you're on the latest available macOS 27 update and add the keyboard behaviour to your existing Apple Feedback report. I'd specifically mention that the freeze starts while moving the pointer through a Stack and that, once it happens, keyboard input stops working in multiple apps, including Terminal.

Use the  Product Feedback - and make it known to Apple regarding this ongoing issue

If it keeps happening, Safe Mode would be a reasonable next diagnostic step. On your M1 Pro, shut down the Mac, hold the power button until Loading startup options appears, select your startup disk, hold Shift, and choose Continue in Safe Mode. Apple says Safe Mode can help determine whether software that loads during startup is contributing to a problem. (Apple Support)

The main thing I'd try to establish during the next freeze is whether the Stack/Dock alone is stuck or the whole Mac has stopped responding. That will tell you whether restarting the Dock/Finder is worth pursuing or whether you're dealing with something broader.

Only as a diagnosis tool  download the Application Etrecheck  ( External Link ) directly from the Developer.

This is a Diagnostic Tool that makes no changes to the computer.

It makes a coherent and readable inventory of both the Hardware and Software used on the computer 

The application is free or paid for added features. 

The Report will Not Reveal Any Personal Information. 

Post back the Full Report - Share Report >> Copy , then  paste  >>>> using the Additional Text Icon  <<<<

Robert Paris wrote:

And I noted as another person posted elsewhere that the keyboard also becomes non-responsive when this happens...

That other person in your other thread did post their EtreCheck report. I was completely unsurprised to see this entry:

[Loaded] CleanMyMac_5_FinderSyncExtension - /Applications/CleanMyMac_5.app

Do you have similar crapware running on your Mac? Many long-time forum members unaffectionately refer to it BrickMyMac, because of the many (many!!) times over the years we have seen the problems it causes. Some approach catastrophic, but many are like what you are experiencing – insidious, apparently unrelated problems after an update to macOS.

From the Intego website:

The Real-Time Scanner protects your Mac continuously by scanning every file that's created, copied, modified, or saved.

That's exactly the sort of behavior that causes problems like the one you are experiencing. A user installs unnecessary 3rd party 'protection' software that uses pervasive, low-level processes, and then has issues with their Mac when Apple makes a change to processes with which that 3rd party software interacts. From the user's perspective, "It's a macOS update problem."

But, it's not. It's just that when a 'regular' app (like my package tracking app, or Adobe Photoshop) is not fully compatible with a new version of macOS (major upgrade or minor update), then after I update macOS that app doesn't work. But those apps are not continuously interacting with all the files on my drive. "Protection' software is, and when that is not fully compatible with a new version of macOS, a wide variety of apparently unrelated things can go wrong.

Mission Control is another example. Yes, there are bugs with it in macOS 27. But in at least some of the cases, users reporting 'glitching, freezing, etc.' behavior subsequently identified the cause as TechTool Monitor...another app that continuously samples drives and processes to 'protect' the Mac from issues. What's the old saying about 'first do no harm'? That applies to physicians, not software developers who want to scare you into thinking you need to pay them for their software to protect your Mac.

Post the Etrecheck Report now or latter is a user's choice

Should it be posted, someone may pickup the report and offer some insights

Predicated on and related to my colleagues observation 👍

Any of the below should be removed as per Developers Instructions 

What follows would only apply if that software or type of software were installed and used on the computer

Disk Cleaner 

CleanMyMac , aka “ BrickMyMac “

There are two schools of thought when dealing with CleanMyMac aka “ BrickMyMac “ or others like this one

The steps in #1 below is predicated on the Offending  Application has been Removed as per the Developers Specific Instruction 

# 1 Some Contributors suggest restarting in Recovery Mode and choosing to Reinstall the Operating System over the existing installation. 

This may or may not replace elements of the  Home Folder ( User Account )  and replace any corrupted or removed elements and make things right.

#2 - Then there are Other Contributors ( like myself ) would suggest  from this link Use Disk Utility to erase a Mac with Apple silicon.

Use the Erase All Content and Settings feature to quickly and securely erase all settings, data, and apps, while maintaining the operating system currently installed.

Thereafter to start from scratch and install all Required Applications directly from the Apple Apps Store or Directly from the Developer minus CleanMyMac

If going this route - It is suggested Not using Startup Assist to migrate things back as this will probably Re-Introduce the existing  issue at the time TM Backup was made 

When it happened again today, I went right to Terminal to run your recommended "killall Dock" or "killall Finder", both of which I tried when I was NOT in the locked Dock mode and they work as you said they would... So when the problem popped up an hour or so ago, I opened Terminal (that worked) but I was completely unable to type into the Command line... I also opened an Excel spreadsheet (just for an example) and that opened fine but I went into a cell and was unable to type anything into the cell... So not only is the dock locked in some strange way but it also disables the keyboard at least regarding typing text.

I have Etrecheck Pro. Used it years ago... Just updated it a few days ago to its newest version and ran it... have the report but haven't looked at all of it myself (not that I would know much of what I was seeing..)... Not sure what to do with that...

Another user in a different post is reporting the same issue, stuck Stack and no use of keyboard, and that person said they're also seeing the issue when running in SAFE mode...

I've also logged into SAFE mode but when I do so, something strange happens, just regarding what it means to be in and how to STAY IN SAFE mode... More about that later...

Thank for the quick and detailed response... Much appreciated... I installed macOS 27.0 about a week ago and this problem started soon after... I've now updated to 27.0.1 and the problem didn't occur for the first day (seen that level of success before) but yesterday it made the error twice in a short period of time... A few days ago I started the MacBook Pro in SAFE mode but didn't actually work with it from there... I think you're suggesting I run in Safe Mode for hours to see if the problem goes away. This is a tough one because I might access the Stack say 100 times with no problem... And then on 101, it happens... I even tried one day to see if I could MAKE it happen but moving the mouse slow, fast or even going out the top of the open file/folder window but NO. I couldn't make it happen... It just does so... I haven't used the Activity Monitor in a long time but I have used it... Will give it a look soon... And though it's been a while, I will likely also open Console and see what I might learn there... Such as in the system.log... I just now opened Console and under Crash Reports, I do see the following (see picture)... Do any of these errors suggest anything about the Stack issue I'm dealing with??? More to follow!!! thanks again...

Again, what the picture lists is what "Crash Report" under the "Console" utility is currently showing...

[Edited by Moderator]

Let me think upon your overall reply and get back to you later

As for the Crash Report you have presented

I have the same crash reports across a M2 Desktop, M4 Desktop and a M5 Laptop, all running Golden Gate 27.0.1

Upon further inspection and the all details there in

These are Simulated Crashes, so I would not concern myself about them

Should the continue to be presented post the Next point update or two.

Then and only then would I be inclined to investigate further

Below is from the M5 Laptop with the latest and created offering from Apple version 27.0.1

Hmmm... Worse than I thought... Frozen Dock happened not at all yesterday even though I used the Dock a good 100 times yesterday... Today, more of the same (OK) until midday when it locked once again... And I noted as another person posted elsewhere that the keyboard also becomes non-responsive when this happens... Could not enter text anywhere, in a text document, inside an Excel spreadsheet and also not within the Terminal APP where I was about to try your input for killall Dock... Or killall Finder... Could not enter text in anyway... Any other way, short of typing text to execute such command???

Hi... I just now saw your response to the other poster who conveyed their EtreCheck report... I have my just created (about three days ago) EtreCheck report but I'm not yet comfortable with showing that entire report to the world. I hear what you say and I don't doubt your expertise. Just not comfortable yet with where I am so far in this problem... If the problem persists and I never get a solution, then I will consider next steps, such as perhaps publishing that Etrecheck report...

That said I do certainly have one of the "crapware" items you alluded to that I've talked about over the years and certainly been pounded on to stop using it by multiple of the Level 9 and 10 users who, no doubt, know way more than I will ever imagine... ... No "cleaners" of any kind... Nope... But I DO HAVE Intego's NetBarrier and VirusBarrier on my Mac... Had them both forever... Have heard all the arguments and please offer more. I am soon to move on to my next Mac computer as this one (M1 Pro, 2021) is getting quite old and has some small but growing hardware issue (keyboard keys mainly). And it's been on my plate throughout to more strongly consider dropping the Intego connection. But today, those two apps I have an always running... Thoughts on whether you might speculate if Intego software (the 2 mentioned) might well be causing this Dock freezing issue... But whatever is causing it, there is NO DOUBT it started with the upgrade from Tahoe to Golden Gate... That much I know... Thoughts???