macOS Sequoia 15.3 wont let me detect my second display

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.

The disconnecting everything solution did not work for me. My monitor goes automatically into power-saving mode. It works fine when connected to a borrowed PC.

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

Re: “My question now is does Apple actually read this support network.”

This is a user to user forum. Apple largely is not here except to moderate it, and is unlikely to see reports of problems unless you contact Apple Support or submit feedback on Apple’s feedback page.

There are other users (not Apple employees) here who can help to troubleshoot causes like trying to use more displays than a given Mac supports. But if you are experiencing problems with a supported configuration, especially ones that seem to be tied to a macOS update, you need to get that information to Apple. Other users here can commiserate, but do not have access to macOS source code, etc. to fix bugs. We are as dependent on Apple as you are.

You may want to include a link to this thread or others that contain detailed problem descriptions when you contact Apple. But they’re not going to notice detailed problem reports here unless you call their attention to them.

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!

I wrestled with this problem after upgrading to 15.3.1. Was about to use Apple Support to erase 15.3.1 and go back to an older version when I stumbled on a fix after reading all the comments in this thread. The display monitor is black - but you can see it in system settings/displays. When I change the refresh rate from 75Hz to 60Hz and then wait about 5-10 seconds, the monitor comes to life. It's definitely a lower quality display, but at least it's working now. Here's a picture of what worked for me. LMK if it helps to solve your problem! Also, Apple still needs to solve this software issue as we need our external monitors to be the high definition we purchased!!

[Edited by Moderator]

Unfortunately, the deletion of the plist file did not work for me...really wish it had!

Since I had NO trouble prior to installing the update, I have no choice but to point at the update as the problem. I also wish there was an easy way to rollback updates that didn't require erasing everything on my Mac Mini M1 and reinstalling everything again...

UPDATE: I just returned from purchasing a new HDMI cable - the cable swap didn't work either. I'm still getting intermittent failure on the monitor where it goes black and then the display returns after a brief period of time (a few seconds to a few minutes). I depend on my big monitors quite a bit, and I am so NOT used to Apple OS updates breaking things upon installation. I left the PC world behind partly for that reason and thought my days of fighting with drivers and updates were mainly behind me...alas, no such joy...

So, Apple - when will we see a patch/fix/solution for this issue?

I was forced to update my mac yesterday (too "old" of OS to use microsoft product... apparently). After the update, not able anymore to connect my monitor.

thank you for the info on the file to delete. That fixes my problem too.

APPLE... STEP UP YOUR GAME FOR F*** SAKE. How can you allow such a problem to happen. For all the non technical people out there, this is going to create a mayhem of frustration and an increasingly bad User experience of your product.

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.

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,

Thanks. It appears Apple does monitor these inquiries, as you appear to mimic the very thing I was told yesterday when I spoke with "Support."

I'm probably betraying my ignorance of such things, but it sounds as if Apple made some changes in the Sequoia OS preventing or inhibiting a further "work around", as you put it. A few suggestions: (1) rather than making "work arounds" required, you might try "work withs"; (2) an explanation of why the old OS worked and the new one does not might go further toward customer satisfaction and understanding than an attitude of what Apple did or did not promise; and (3) pointing the finger elsewhere is never a good strategy in seeking continued patronage.

As this site appears to attest, there are a lot of customers like myself who rely on multiple screens.. I would think the good folks at Apple would look for ways to accommodate those with this need in the design of their OS, rather than prevent it.

Thanks Servant.

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.

Came across a clients 14" MacBook Pro (M3) that had this issue with a large (42" or so) curved LG Thunderbolt Display.

Followed most of the instructions below with no luck. Deleting the files mentioned below and restarting did not work as is.

What finally DID work was downloading the Display Menu app and using that to get the Mac to finally see/detected the monitor and allow me to extend the displays.

My recommendation:

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

Download (App Store) the Display Menu app. Open the menu and it should detected your screen and allow you to extend (or mirror) your display.

Director of IT - major college at a large Big10 university