macOS Sequoia 15.3 wont let me detect my second display

It was easy to just trash this file: apple.windowserver.displays.<hex_string>.plist : and restart and problem solved.

I have a different problem on sequoia 15.5, I wrote about it here: Mac OS Sequoia 15.5: Bugged desktop windo… - Apple Community

Sometimes it works to simply use a different Thunderbolt Port, but I had to use a completely different Thunderbolt to HDMI adapter to get the Mac to recognize the external monitor.

Once it recognized the monitor on the new adapter, I was able to switch back to the old adapter and it continued to work.

Hi, after trying out different cables, checking the connections, realized that just allowing about 30 - 40 seconds for the display to come up in the external monitor helped to resolve the issue in my case. The external monitor was keep trying to pick up the signal and saying "No signal found" and "Entering into Power save mode", after about 3 / 4 tries, the display started to come up with no issues. I've not used any of the commands recommended in this Forum as this is corporate laptop and I was not sure of my level of authorization in it.

Hi. I experienced the problem directly coming into 15.3. Couldnt solve it whatever i did. Called apple in greece and they provided this remedy. Working fine since even after shutdowns and restarts. Cheers

It's very clear there is an issue with this update, the internet is full of it, already at least more than a month. No solutions worked for me. This is 100% a software issue on apple's side. I need the second screen for work and it affects my productivity a lot. When will Apple fix it?

It seems that many people, including myself, are experiencing the same issue. After installing the new OS Sequoia 15.3, my second monitor, which I previously connected via a Thunderbolt cable, is no longer being detected as it used to be.

This issue is causing me significant trouble, and I want to know if anyone has already found a fix for it.

I have also tried to find a way to downgrade the OS, but I couldn't find any clear instructions on how to do it.

I would like to request help from anyone who is facing the same issue or has already solved it to share their solution with me.

I have no idea why this problem occurred, how long I have to wait for a fix, and I sincerely hope that Apple will resolve this issue as soon as possible.

Sad!

I have MBP M4 Pro and two external displays. One Dell and another one portable display via type-c.

Right after macos update the second display went off. And I tried everything here, restarts, unplug, all ports etc.

It doesn't work. But Dell is working fine. Before the update, on 15.2 everything worked very well.

Just adding my voice to the chorus of infuriated customers here! Brand new iMac connected to my Apple thunderbolt display from a few years ago - it worked great until I updated to 15.3 and BOOM the display is no longer recognized. I tried connecting it to my 2023 Macbook Pro running 15.3, same results. I've tried all of the troubleshooting methods and nothing has worked. Meanwhile, a 10 year old LG monitor is recognized by my new iMac immediately via HDMI with no issues. So for now, my awesome Apple display gathers dust while my much-less-awesome old LG monitor fills in.

Ridiculous.

Here is my problem and how I fixed it.

The problem:

Monitor connected via hub would not show anything, but I could move my mouse to it and some windows were moved there for sure, so my mac recognized it, but did not show anything. If I connect the same monitor via hdmi directly it worked, so whatever monitor is connected via hub did not work.

Solution:

May not work for everyone.

1. Go to System Settings.
2. Displays
3. If you can see a monitor you are having problem with, click on it and change the color profile several times, eventually it may work again, from there you can change the color profile to the default one. Attaching the screenshot.

P.S.: Not sure if it is a temporary solution or it fixes the problem completely, just fixed it and decided to share. Good luck.

edit: Just checked. When I disconnect and reconnect the monitor the problem is the same, but now I can fix it pretty easily by chaning color profile or refresh rate (apparently does the same thing I guess- refreshes some configs on laptop side).

I used to have two external monitors connected to my Mac: one via HDMI and another via USB-C. After updating to version 15.3.1 (24D70) yesterday, macOS now only recognizes one of them. The second monitor turns on but only mirrors the first one, and I can no longer extend the display.

First, I ran this command:

sudo find / -name "*windowserver*" 2>/dev/null | tee ~/Desktop/windowserver_files.txt

Then I analyzed wherever the plist files are there.

Then this

sudo rm -rf /Library/Preferences/com.apple.windowserver.*

Then I rebooted. It worked for me. I upgraded to 15.3.1 hoping it would fix the issue but it did not.

Has anyone found the fix yet? After connecting the macbook it just gives a black screen

I have a Macbook Pro M3 with MacOS 15.3.1

External monitor is LG LG 27UP650-W 4K HDR monitor

1. Tried a new HDMI to HDMI cable, did not work - infact the cable you get with the monitor is working with my other mac running on macOS 15.2 (INDICATING SOMETHING IS DEFINITELY WRONG WITH 15.3.1 update!!)
2. Tried switching from HDMI1 to HDMI2, still gives a black screen
3. Tried deleting .plist file from preferences and restart mac, still same issue (new file gets created as soon as I plug the HDMI cable in, but the result is still the black screen)
4. Tried unplugging EVERYTHING and PLUG IN again, still the same black screen

I am almost sure now its not a hardware issue - be it the cable, the monitor, or macbook HDMI port, because its working when I connect to a TV, this issue is only happening with the monitor

Everything works as expected when I connect it with my personal Macbook Pro with M1 Pro chip and MacOS 15.2

Please help :(