Macs are hailed for their user-friendly interface and features, but these do not spare them from errors. There’s Mac error code 50 and Mac error 924 as examples, which we have both covered and helped troubleshoot in the past.
But has there ever been a time when you are using your Mac supposedly in peace, and out of nowhere an error pops up? Here’s a case in point: the error message “WindowServer [ERROR] – Unknown CGXDisplayDevice: 0x41dc9d00” showing up in the Console. What is this bug all about?
If you have encountered this error, then know that you are not alone. There are Mac users who have come out in the open to complain about the error message. Most of them find it every time they use Mission Control in High Sierra, with their computer crashing several times. The error is also commonly reported in macOS High Sierra 10.13. It comes not just with device crashes but with video issues as well.
Let’s get into a quick definition of terms. Mission Control provides a bird’s eye view of your open windows, desktop spaces, full-screen apps, as well as Split View spaces, making switching between them easier and more convenient. The Console, on the other hand, is a log viewer developed by Apple and included with macOS. It permits users to search through all of the logged messages in the system, alerting the owner when specific types of messages are logged. It is typically used for troubleshooting a problem with your Mac.
Pro Tip: Scan your Mac for performance issues, junk files, harmful apps, and security threats
that can cause system issues or slow performance.
Special offer. About Outbyte, uninstall instructions, EULA, Privacy Policy.
Those who are faced with the CGXDisplayDevice: 0x41dc9d00 error need not look far and wide for a solution. There’s only one thing to focus: the Bartender app. Let’s dig deeper into the issue.
What Is Bartender?
The Bartender app allows you to organize your menu-bar app through three different ways:
- Hiding them
- Rearranging them
- Moving them to Bartender’s Bar
You can choose to display the complete menu bar, opt to have the menu-bar items shown in the menu bar once they have updated, or keep them constantly visible in Bartender’s Bar. The Console lets you tidy up your menu-bar apps in your own preferred way, hide apps that you need to run but would rather not see, or achieve the clean and organized-looking menu bar you’ve always wanted.
Bartender requires Intel, 64-bit processor along with macOS 10.12 or later versions. In its version 3.0.47, it fully supports macOS Sierra, High Sierra, and Mojave. It prompts for accessibility authorization, supports dark mode, and is notarized for further security.
What Is Its Role in the Error?
Apple and Bartender have somewhat openly admitted that one cause behind the error is a public API. Thus, it is no coincidence that Bartender 3 is running and there are a couple of Window Server errors with the CGXDisplayDevice: 0x41dc9d00 error message.
As of macOS 10.13.4 Beta 1, Apple seems to have already fixed the error message, so it shouldn’t be showing anymore. The hope is that the error message – even though its constant logging is said to be harmless – will altogether stop with the proper release of 10.13.4.
Therefore, the quick route to a solution is to quit Bartender 3 app and see if the messages persist.
The Error Is Still There. What Should I Do?
If quitting Bartender 3 does not seem to work in your favor, then you can pursue other troubleshooting steps. Here are some solutions to try:
- Make it a habit to always clean up and optimize your Mac for speedy and stable performance. A third-party tool such as Mac repair app can do the required due diligence and get you the optimal systems operations you deserve.
- Update all your third-party software to their latest versions.
- Boot your computer in Safe Mode if the error message persists.
A couple of Mac users online also notice that the error message shows in the Console alongside graphics glitches that have manifested every since they upgraded to High Sierra. From there, random black boxes have been popping up in Safari, iTunes, and other apps.
Sensing a connection, they found a fix by going to display preferences and selecting another color profile. Simply launch a website where the black boxes appear, and then reload it every time you change the profile.
Final Notes
The error message “WindowServer [ERROR] – Unknown CGXDisplayDevice: 0x41dc9d00” can show up in the Console of your Mac due to the active presence of the Bartender 3 app or an entirely different reason.
While considered harmless, the error messages can be unnerving, so you can try the quick troubleshooting steps we provided above. But feel free to tell us about your own experience and what worked for you!
I am having this problem in macOS High Sierra 10.13.6 with Security Update 2019-005 on an iMac mid-201, so the problem definitely was not fixed by Apple earlier, regardless of what they published. And I don’t even know what the Bartender App is, nor have I ever downloaded it to my Mac, so that is not the answer either. This is an Apple problem. Pure and simple. And one that they have not fixed for quite some time. My Mac keeps rebooting right in the middle of Apple apps or at log in or even before log in. Reinstalling macOS High Sierra from the Recovery Drive has not helped. Not with Command R. And not with Option Command R. There is something very wrong with macOS High Sierra 10.13.6. My hard drive tests okay. It’s not a hardware problem. It’s Apple’s operating system.
I never used Bartender and a full check of my disk using EasyFind does not show any occurence of a “bartender” file either visible or invisible.
However, with High Sierra (10.13.6) my Console (Errors and Faults) is crowed with:
“[ERROR] – Unknown CGXDisplayDevice: 0x41dc9d00”
Thus the Bartender explication is not enough.
Thus the statement below is wrong:
“As of macOS 10.13.4 Beta 1, Apple seems to have already fixed the error message” .
The following is too vague to be helpful:
“Apple and Bartender have somewhat openly admitted that one cause behind the error is a public API.”
I am running High Sierra 10.13.6 on
Model Name: iMac
Model Identifier: iMac12,1
Processor Name: Intel Core i5
Processor Speed: 2.5 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 12 GB
Boot ROM Version: 87.0.0.0.0
SMC Version (system): 1.71f21
I get a few or hundreds of small blinking squares that are so bad some times they lock up the computer. While this is going on I see the CGXDisplay error over and over. I can make all this stop by using Quartz Debug to disable 2d acceleration. These blinking squares are set off by starting Thunderbird. If I never start Thunderbird I can leave 2D acceleration on. I have run Apple advanced hardware diagnostics for hours with no errors. I have uninstalled and reinstalled Thunderbird.. This has nearly made me crazy trying to find a fix. I can email you screen shots of both the logs and the blinking squares.
To say “There’s only one thing to focus (on): the Bartender app” is not correct. I don’t have Bartender installed and never have but I get this error too ‘Unknown CGXDisplayDevice: 0x41dc9d00’. Do you have any other advice for this error?