macOS Sequoia 15.3 wont let me detect my second display

I have the same issue here. I escalated this to Apple support Germany to increase more awareness. I hope this will be fixed soon.

This has nothing to do with the displays, monitors,... in my opinion. I have been using the same setup with my old MacBook Pro and new MacBook Pro for about 5 years. Two external monitors - one display port / one HDMI. I have NEVER had an issue with the external displays coming online until upgrading to 15.3. It is always the HDMI display that does not come back after the system sleeps.

I have found that power cycling either the monitor (easier of course) or the laptop will bring all three back online and they will all remain fully functional until the next time it sleeps.

Hello everyone. This solution worked for me. I panicked when after updating to Sequoia 15.3.1 my hub stopped being detected by my Imac M1. I use the hub for the Ethernet cable, the SD cards, a couple of USB connections for external SSD from time to time, and my second screen which I almos depend on. Try this before deleting files!

To Apple, when will the second external monitor issue be fixed? I have MacOS 15.3.1 on my M1 MacBook Pro. I have the same problem others have encountered. I've tried all the proposed solutions and it still does not work. I have been using two external monitors (and my MacBook pro monitor) for about a year with earlier MacOS versions with no issues.

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 managed to fix it. It was a combination of the discussed solutions in this thread.

• Disconnect the non working displays from usb c as well as power for some minutes
• Delete the library/preferences/byhost/apple.windowserver.displays.plist file
• Delete Trash

I repeated this procedure 3 times until each display works.

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

Same issue. Using my external monitor with MacBook Pro with no problems until the update. Issue started immediately after the 15.3 update. It takes me different steps when I come back to the office to get it to work. Sometimes power, sometimes unplugging cables, flipping the cable... today, it took all those steps numerous times before it finally recognized.

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!

To be constructive, after rebooting and tearing up a bunch of wiring, all with no effect, I installed an app (from the Apple app store) called "Display Menu". In my case, I could tell that the MacBook was *kind-of* seeing my external monitor (which as with everybody else here has been working for months before 15.3). I could tell this because the monitor, instead of showing the TV error about there being no HDMI signal, was showing a message clearing coming over HDMI from the mac telling me to choose the display mode (in a weird way that makes no sense). The "Displays" settings thing, the MacOS one, however did not see the monitor. With that "Display Menu" app installed, I got a little widget in the menu bar that *did* see the external monitor, and it let me choose it as an extended display. Now it works fine.

Again, I want to be clear in my opinion here (which is very important :) that this is an OS issue. Maybe Apple has some idea of a new/improved/different feature, but it does not work properly now whether it's a good idea or not.

Got excited when I saw that 15.3.1 was released today - really hoped that there would be a fix for this VERY ANNOYING AND OBVIOUS software issue. But alas, my tunderbolt display is STILL not recognized.

Saw 15.3.1 appear last evening and IMMEDIATELY tried to put this on. I have tried many of the "solutions" even knowing it was DEFINITELY 15.3 that is the cause.

Unfortunately this version did not address this issue for me and it persists. Hoping Apple can get this fixed as it is simply annoying to have to cycle one monitor every time I sit at the machine after a break. Definitely ruins the experience they strive so hard to present!

Servant,

I am well aware of the technical specs on the M1 and have been for some time. I was aware that the specs purported to limit one to two displays, the iMac display and one external.

I researched the matter and discovered that despite that spec it was possible with a Satechi Thunderbolt DisplayLink docking station to run two external monitors. I bought the docking station and did in fact run three displays at once. This would seem to suggest that, at least when running Sonoma the M1 chip was up to the task, despite the specs you reference, of running three display monitors.

You appear knowledgeable; I would appreciate your insight. Why is it that an iMac M1 running the Sonoma OS was capable of generating three displays through a docking station, but the very same computer running the Sequoia OS cannot. I'm not a techie, but it seems logical that something changed and the only thing that changed was the OS. If Sonoma could provide three screens, why can't Sequoia?

Unless Apple wants to for some reason discourage use of docking stations.

Appreciate your time and your expertise.

RetiredLegalBeagle wrote:

I have the same issue. My desktop is a 2021 IMac M1. When operating Sonoma, I had two external Dell monitors working, in addition to the main display, through a DisplayLink Plug and Display Hub. One monitor worked with a thunderbolt to HDMI cable and one worked through a HDMI to HDMI cable. No problems. Worked like a charm. Download Sequoia yesterday and monitor on HDMI to HDMI is black. "No HDMI signal...." Called Apple; spoke to less than sympathetic tech who said my problem is with the DisplayLink folks. "But," I said, "there must be something in your new OS since it worked fine in your old OS. She said, "I'm sorry."

The iMac (24-inch, M1, 2021) supports a maximum of one external display.

iMac (24-inch, M1, 2021) - Technical Specifications - Apple Support

You connected two – at least one of which you connected in an unsupported fashion, using a workaround.

One drawback of using a workaround is that, if there is any change that breaks it, you must rely upon the third parties who supplied you with the workaround to fix things. Apple never promised that you could attach more displays than the Technical Specifications say that you can.

My guess would be that if you contact the company that manufactured the "DisplayLink Plug and Display Hub", they will point you at Synaptics. Whether Synaptics has new versions of their drivers that fix the problem yet, I don't know. But that's the site you will probably need to keep monitoring.

Synaptics – DisplayLink Graphics

DisplayLink Support – Troubleshooting: macOS

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 :(