macOS Sequoia 15.3 wont let me detect my second display

Thanks a lot, sangy987.

I was struggling with this issue ever since I upgraded to macOS Sequoia 15.1.

I'm now on Version 15.3.1 (24D70), and your solution worked perfectly for me.

My external display, the Samsung C49RG90, is now detected, and I can use the highest 5K (5120 x 1440) resolution.

Delete ~/Library/Preferences/ByHost/apple.windowserver.displays.<hex_string>.plist and reboot

I can confirm this worked for me on version 15.3.1 - I have three external monitors + the MacBook Pro screen.

It may or may not make a difference, but I disconnected the monitors, deleted the file, shut down and restarted before adding each monitor one at a time.

I believe that is the case for the M1 Mac Mini, perhaps one of the laptops. The Mac Studio M1 I have supports three monitors because that’s what I’ve been doing for over two years. But I do have a Kensington TB3 dock where two of my monitors are plugged into. I would also guess the first M1 Mac Pros support at least three or more monitors.

That solution worked for me. However, I do not believe you need to download anything. I didn’t. Since it’s a .plist, if you drag the file to your desktop and reboot, the operating system will create a new .plist file. You’ll need to go in and manually set your preferences again, though.

I waited until 15.3 because of all the reported issues with multiple monitors. For me, at least, there are still issues with 15.3. I have a MBP16 with 2 Apple Thunderbolt Monitors.

Both monitors work for me.

HOWEVER, I have to reboot every morning to get both monitors to work. When waking up from sleep, only one of the Thunderbolt monitors is recognized. Restart MBP and back to both Thunderbolts working. A pain but at least they work.

Running 15.3.2 here and the nothing has fixed this for me. I have tried all of the suggestions in this thread and none of them work for me. It definitely came with the 15.x releases and I suspect only Apple can actually provide the fix going forward. Just unfortunately has not been in the two updates released to dae.

"Luckily" for me simply power cycling my monitor wakes up this display until the next time it goes to sleep. It continues to be aggravating to say the least.

I tried this. It allowed my monitors to connect and be detected, but my MacBook Pro (M2 Pro Chip) will not detect power from the Thunderbolt. I deleted the file you described, but I have to plug in a power source, in addition to the Thunderbolt, in order to run multiple displays with the laptop closed.

This just happened to me two days ago. I thought my cable had failed, and I ordered a new one. Next day, it after the cable arrived and replacing the cable proved useless, I searched and found this thread.

I first tried moving just the more narrowly focused file at

mv /System/Volumes/Data/Users/<myusername>/Library/Preferences/ByHost/com.apple.windowserver.displays.<hexadecimal-uuid-value>.plist ~/Desktop

and rebooting, but nothing changed.

Then I moved the file at the more general /Library/Preferences location:

sudo mv /Library/Preferences/com.apple.windowserver.displays.plist ~/Desktop

and rebooted, and all is well.

What is crazy is I had run the OS update a few days prior, and had no issues when I plugged the external monitor in. It was only when I switched inputs & cables for the external monitor that the problem suddenly appeared, but even switching back to the original input and cable, the issue persisted. FWIW I'm using a USB-C to DVI cable to drive a 49" Samsung Odyssey G9 from an M3-equipped MacBook Pro; the cable I'm using allows the monitor to run at 120Hz (limit of the Mac hardware). None of that matters for this issue. But I'm including it in case doing so helps others find this post when they search.

Hello Magic,

When you say:

"Then I moved the file at the more general /Library/Preferences location:

sudo mv /Library/Preferences/com.apple.windowserver.displays.plist ~/Desktop

and rebooted, and all is well."

Where did you move it to? Desktop - trash - etc?

Also not sure you have the answer but, I don't seem to have that particular file in the location that has been pointed out. When I was on with Apple Support, the team member had to send it to me, then I had to delete it (lol) as per all the other outlines that refer to this particular file.

Do you have any insight on that, or anyone else reading this for that matter.

My system

14-Core CPU

20-Core GPU

48GB Unified Memory

1TB SSD Storage¹

16-core Neural Engine

16-inch Liquid Retina XDR display²

Three Thunderbolt 5 ports, HDMI port, SDXC card slot, headphone jack, MagSafe 3 port

Magic Keyboard with Touch ID

Force Touch trackpad

140W USB-C Power Adapter

Sequoia 15.3.2 (this was the update. I'm not exactly sure what it was shipped with)

It's brand new only I've only had it a week.

Thanks

It appears for me at least that the 15.4 release has resolved the issue - or at least three times my monitor has come back on its own. I tried ALL of the other "fixes" and none of them worked for me. Hoping I have not just cursed myself.

Latest Update: I spent quite a bit of time today reading through this forum, documenting and trying different fixes, to no avail. I decided to go the Apple Support route so at least it would be documented with them, since I've been told they don't check this community or the posts.

After waiting for a while, I was connected with a support tech and we tried restarting in "Safe Mode" (i.e. hold the Shift key when restarting my Mac Mini M1) and that did nothing to help the situation. I'm on their schedule for a call tomorrow (Saturday) morning at 9:15 to continue troubleshooting.

Fortunately, I have my iPad to chat with Support while we are trying to make changes to my Mac Mini. I just hope a good night's sleep (for me) and documenting what they tell me to do will help convince them the update (Sequoia 15.4, installed a few days ago) is the source of the problem). I'll try to document what they tell me, and will report back what the end result is.

Wish me luck!

Not working for me either.

Deleting the windowsserver.displays.plist file does work for one re-boot, then the next time it sleeps for any amount of time it's the exact same problem again. I have MBP16 and 2 Apple Thunderbolt Monitors. My current work flow is to start the day by disconnecting the Thunderbolt monitors (daisy chained), deleting the plist file, rebooting, reconnecting the Thunderbolt monitors, hope all the USB devices are recognized (usually, but not always), re-arranging the displays to the way I want and make sure the machine does not sleep during the work day. Frustrating...

I ran this setup with NO issues for YEARS until Secquoia.

100% an OS issue.

I'm another person with this problem and deleting the .plist file mentioned earlier in this thread (and restarting) seems to have fixed the problem a couple of times.

I don't think it's a permanent fix though - as I say, I've had to do it more than once.

I note that that .plist file deosn't re-appear immediately after restart. I am going to keep an eye on it, to see if its reappearance is linked to the problem starting again.

In fact on the latest occasion I found two of those .plist files. I noticed that they were dated 2015 and 2021. So is the system somehow copying them over from some previous configuration setup?

I have an M1 mac mini and this extra display not getting recognised has been an issue since the start. Before Sequioa I could resolve it by switching the monitor on and off and/or sleeping and waking the computer.

Deleting the .plist file (and restarting), as mentioned earlier in the thread, seems to work for me. However I don't think it's a permanent fix - the problem can reappear in which case it's necessary to do it again.

I have an M1 mac mini and the second display has been problematic since the start, often failing to be detected. Sometimes there's also an issue with the main monitor going blank - probably somehow related. Previously, putting the Mac to sleep and waking it and/or turning the monitor on/off usually sorted it but these techniques stopped working with Sequoia.

Like others I have a third monitor attached via displaylink.