macOS Sequoia 15.3 wont let me detect my second display

Same problem for me. I’ve tried all the fixes in this page and nothing has worked. It’s taken me 3hrs.

Thats 3hrs away from study for my final exam.

I’ve given up. Im going back to my study with the limitations of only one decent sized screen. So disappointing that Apple refused to allow us to work with more than one reasonable sized screen. Am convinced that this update & subsequent problems are all part of Apple’s need to make us do things their way.

Thanks for nothing Apple 🥺

I am having a similar issue since the 15.3 update and it is very frustrating to not be able to extend the displays in a reliable way any more. If I unconnected and connect eventually it will finally find it but it has been taking 20 minutes every morning to get his working. Do we have a timeline with this will be fixed. This is a horrible user experience.

This is still going on for me! There was an update and still not fixed, which seems quite remarkable. I've got a rather expensive laptop and for months haven't been able to use another screen with it. I've tried everything that's been discussed here.

Am I alone here? Can someone provide an update as to when it's going to be fixed?

Unfortunately, the delete 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 my my Mac Mini M1 and reinstalling everything again...

If you get to the point where the Mac is putting up that "Choice" display, then you're almost done. That tells you that the computer does know the monitor is there. This is the point at which that "Display Menu" app might help. It's free, and as far as I know it is not evil and it did help me. I installed it and it made telling the machine what I wanted easy.

To clarify when I say I "moved" the files -- I always play it "safe" when doing these sorts of interventions. Rather than simply deleting the files, I simply moved them to my desktop, as shown in the terminal commands I shared. After I rebooted and found my issue was fixed, I did follow up and delete the two files I'd moved to my desktop, as I clearly did not need them anymore. If I had encountered an issue, moving them to my desktop would have allowed me to restore them to their original location.

cc: Cparr5150

This is a bad Joke, I am facing the same issue, tried all the suggestions here until now,but none worked. I made it work by switching from the HDMI to a USC-C port, but now I have one less USB port to use for work!

WHEN THIS IS GOING TO BE FIXED?!?!?!?!

I thought that my 10-year old monitor finally died, when it stopped displaying anything all of the sudden, regardless of whether I connect it through HDMI or USBC. And I bought a new monitor.

Turned out I was wrong - it's still very much alive. It works when I connect both monitors at once with USBC's.

It just doesn't get detected by my Macbook when I connect it on its own. Doesn't show up in the list of displays, and option+Detect Displays doesn't work either.

I tried everything, and it was this that seemed to trigger the monitor being detected again for me! It started with 15.4 and persisted with 15.5. I finally got it working today by completely unplugging the thunderbolt cable, turning it around and plugging it back in again (maybe it was just fully unplugging both ends rather than turning the cable around, I'll probably never know).

For context, I have a MacBook Pro 16 (2021), plugged into a Thunderbolt 3 Anker dock via single cable to provide power and monitor connection (4K monitor is connected to the dock via HDMI). After upgrading directly from Sonoma to Sequoia 15.4 my monitor was no longer detected. I upgraded through a couple of bugfix versions, before getting 15.5 today, and still no luck. I was having to plug the monitor into my MacBrook Pro directly via HDMI in order to get some work done... until today when I tried unplugging everything (only 1 TB3 cable and 1 HDMI cable), plugged the HDMI cable back into the dock, turned the TB3 cable around, and hey presto, the monitor came back to life.

phaed2 wrote:

I tried everything, and it was this that seemed to trigger the monitor being detected again for me! It started with 15.4 and persisted with 15.5. I finally got it working today by completely unplugging the thunderbolt cable, turning it around and plugging it back in again (maybe it was just fully unplugging both ends rather than turning the cable around, I'll probably never know).

For context, I have a MacBook Pro 16 (2021), plugged into a Thunderbolt 3 Anker dock via single cable to provide power and monitor connection (4K monitor is connected to the dock via HDMI). After upgrading directly from Sonoma to Sequoia 15.4 my monitor was no longer detected. I upgraded through a couple of bugfix versions, before getting 15.5 today, and still no luck. I was having to plug the monitor into my MacBrook Pro directly via HDMI in order to get some work done... until today when I tried unplugging everything (only 1 TB3 cable and 1 HDMI cable), plugged the HDMI cable back into the dock, turned the TB3 cable around, and hey presto, the monitor came back to life.

Update: After my MacBook went into sleep mode overnight, it woke up this morning with no access to the external monitor. So back to square 1 for me... I'm not convinced there is a reliable fix for this until Apple fix the issue.

I have a cheap separate monitor I bought from China, after upgrading to 15.5 it still doesn't recognize this monitor, I tried deleting com.apple.windowserver.displays.*.plist but it didn't work either.

Nothing worked except this: I disconnected the main monitor, restarted the computer with the second monitor. Once it detected the second monitor, I connected the main one. It worked until I restarted the computer.

THIS WORKED!! read below:

Forget about NRam reset, Hz settings, new cable, hub or disconnect everything:

I just created a guest account and external monitor showed up. Then I logged out and back to my main account and the monitor is still there.

This is a great fix,

I have been facing the same issue from yesterday. Even had a call with apple support , and about 3 hours ,

Still can't fix. At last they even made me reinstall the os , and still didn't fix. Now this solved my issue.

Thanks

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