Can not turn off automatic tiling when a file dragged to top of screen in macOS 27

Have you rebooted your Mac? If not, that's the first step. If that does not help, then see if the problem is present when you boot in safe mode. That process performs some system cleanup and clears caches, andalso disables 3rd party extensions that may cause problems.

Start up your Mac in safe mode - Apple Support

If that does not correct the issue, test in a new user account. A newly-created user account will have all settings at default, and if the issue does not occur in that new account then it provides guidance on what may need to be changed to correct the issue.

Add a user or group on Mac - Apple Support

Once the testing is complete, the new account can easily be deleted.

Delete a user or group on Mac – Apple Support

Those steps will help to isolate the problem.

It might help to download and run EtreCheck, written by a long-time forum member. The free version is fine. Post the full report using the Additional Text button. No personal information is revealed.

I cannot replicate the issue you describe. The automatic tiling settings are off on my Mac, and when I drag a window to the menu bar, it just sits there. I suspect it is one of your third-party extensions, perhaps one sitting in the menu bar, that is causing this problem. Safe mode would confirm that.

The observation that the problem occurs in safe mode but not in a new user account does indicate a corrupted .plist file. The most likely culprit (the one where the automatic tiling preferences are saved) is:

~/Library/Preferences/com.apple.WindowManager.plist

Generally speaking, .plist files can be deleted and macOS will simply recreate a clean one. You'll have to re-set your desired preferences, of course.

I used commercial/paid Gemini AI and it reported that "This issue stems from a confirmed bug in macOS 27 (Golden Gate) rather than a corrupt user profile. Other users encountering this exact issue—such as in Apple Community thread 256372439 and related developer forums—have identified why all GUI toggles and Terminal commands fail to stop it:"

Problem started when I upgraded to macOS 27. Curious that it did not occur on a newer macStudio in my office that has a nearly identical setup.

Probably not worth submitting a bug report if others have already reported.

thanks anyway

This info was helpful: Safe Boot did not solve the problem so I assume any third party apps that load at startup is not a problem. Creating a fresh new user and logging in with the new user solve/prevented problem.

This is a Mac13,1 with this problem. At work, I have a Mac14,13 that is running same macOS (Golden Gate) with nearly identical software and this is not a problem.

Deleting this user and restoring manually will be a mess - particularly for items like stored emails in Library using Apple Mail. I suppose I can delete user but IT department may block a restore (it does for a macOS reinstall). If I can use Time Machine restore, I suppose I could try that but it may restore problem too???

I tried my commercial Gemini AI for advice and have a long report where I tried a variety of suggestions. None worked. Gemini said "This behavior is caused by a hardcoded OS-level regression introduced in macOS 27 (Golden Gate), not a misconfigured preference or damaged file. PDF + 1 Other users encountering this exact issue—such as in Apple Community thread 256372439 and related developer forums—have identified why all GUI toggles and Terminal commands fail to stop it:"

I suppose I'll send a bug report. It's curious that this problem started when I upgraded to macOS 27, but did not occur on my office MacStudio that has a very similar setup.

I will hold off on creating a new user. thanks for the advice

I have apps like Scrambler that recognize a file by dragging to app icon in menu at the top of the screen,

That’s weird. I don’t think that the status menu can normally respond like that. I wonder if it is an interaction with the app hacking the OS. Starting up in Safe Mode would likely disable that if it is the app modifying the system, but you may have to uninstall the apps to see if they are the cause.

hmm, in desperation I deleted all the .plist files in my ~/Library/Preferences including system-related and any invisible ones, and unfortunately the problem has continued.

I suppose I could move all my files/folders in User folder to a second drive except Library folder, and then delete this user and create a new user; then move these files into the new user. Of course, all preferences will be lost which is a hassle

Alf2001 wrote:

problem in macOS 27 for tiling of windows when a file is dragged to the top of the screen. I turned off the tiling in settings in Desktop & Dock settings in Mission Control (and Windows) but it still tiles windows. This did not happen in previous macOS. I have apps like Scrambler that recognize a file by dragging to app icon in menu at the top of the screen, but now I get activation of mission control like tiling of windows, so apps aren't usable. Any advice? Thanks

see if this is it... make some changes and compare your results

"Drag windows to top of screen to enter Mission Control" is kept off on this computer, so it was turned off when I first got the MacStudio and is kept off. So not the problem.

In Desktop & Dock settings for Windows and Mission Control, all are turned off, I restarted Mac, and problem persisted. thanks

I suppose I'll need to check with my IT dept. since they blocked used of Migration Assistant, or I'll need to delete offending preferences if I can figure out which one?

deleting ~/Library/Preferences/com.apple.WindowManager.plist didn't fix the problem