User level: Level 1 (6 points)Why are Mission Control window previews always black after updating to macOS 27?
After updating to macOS 27, the window previews in Mission Control have become completely black. The desktop preview displays normally, but every open app or window preview is black, as shown in the attached photo. This happens every time I open Mission Control, regardless of the time or which apps are currently open.
How can I fix this and restore the normal window previews? Is this a known issue in macOS 27?
Posted on Sep 22, 2026 8:59 PM
User level: Level 9 (74,110 points)Sep 23, 2026 4:18 AM in response to yao294
Restart your Mac: A standard reboot occasionally forces the window server to clear cached graphical data and redraw previews properly.
Reset NVRAM/SMC (Intel Macs) or Force Restart (Apple Silicon): Shut down completely, wait 10 seconds, and turn your Mac back on.
Check for background utility conflicts: Certain third-party menu bar or window management apps can hook into Mission Control incorrectly and trigger blank placeholders. Try quitting running background utilities to see if a specific app is causing a conflict.
User level: Level 9 (72,871 points)Sep 23, 2026 4:34 AM in response to yao294
There have been many issues reported with Mission Control on macOS 27 Golden Gate, especially regarding the way Full Screen apps are handled. Some have been resolved by identifying and removing incompatible 3rd party extensions, others are bona fide bugs.
There have been many issues reported with Mission Control and Spaces on macOS 27 Golden Gate, especially regarding the way Full Screen apps and app switching are handled. Some have been resolved by identifying and removing incompatible 3rd party extensions, others are bona fide bugs.
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.
If the issue persists in safe mode and a new user account, that suggests that it's a bug that Apple needs to address. Bugs can be reported to Apple here:
Reporting issues like this to Apple is the only way to get them fixed. They do prioritize bugs based on frequency of reports, so the more people who report it, the faster it will be addressed.
Personally, I have not seen the issue you report – thumbnails are normal in Mission Control for me.
User level: Level 9 (72,871 points)Oct 1, 2026 1:46 PM in response to whither
whither wrote:
It only affects my main user though.
If the issue occurs in one user account but does not occur in another user account, that suggests corrupt preference files for the affected account.
Delete problematic preference files
~/Library/Preferences/
Sep 23, 2026 1:18 PM in response to yao294
This is happening for me as well. Tried restarting my mac but didn't help. I installed all the latest updates.
User level: Level 1 (14 points)Oct 1, 2026 1:16 PM in response to yao294
I am also experiencing this and it is super frustrating. I have tried restarting, resetting NVRAM/SMC. No weird plugins or modifications installed. It only affects my main user though.
Originally posted at discussions.apple.com/thread/256363186