macOS Sequoia 15.3 wont let me detect my second display

Same here - just updated a Mac Studio to 15.5, and it borked the second monitor.

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

this is the fix. 15.5

Unfortunately, this fix did not work for macOS Sequoia 15.5 but thanks for sharing.

same here. After updating to 15.5 it my external display, all black, tried all the NVRam Reset and deleting the display file from Preference. Nothing helped yet.

[Edited by Moderator]

👍🏽

Edit: fixed it by creating guest account.

external display showing up again

then Log off and go to your main account

This worked for me. Thank you, buddy.

What worked for me was changing the USB port that my USB hub was connected to + changing the orientation of the cable when plugging in the cable of the USB hub.

this worked on sequoia 15.5

I too had the same issue. I rebooted a few times and still prevailed. I unplugged my thunderbolt hub where my displays are connected via HDMI and that still didn't work. It wasn't until when I pulled the HDMI cables and switched them that for some reason the displays detected again and all is well. Best of luck!

here's the solution. close the mac. disconnect ALL cables (all!). close the monitor or just disconnect ALL its cables. wait 5 minutes. reconnect and boot all devices. worked for me and I had the exact same problem.

@geapgr - Are you saying this was a permanent solution for you? Were you experiencing this issue every time the system went into sleep mode - which is only where I am seeing it? Will of course give it a try, but sadly have just made power cycling the HDMI monitor part of the startup process. Hoping for 15.3.1 and a resolution!

Ok I fixed it: after trying everything I could read everywhere, the solution for me was very simple and strange:

I pulled the usb-c thunderbolt cable out of my second screen, then flipped it (so the usb-c thunderbolt that was in the MacBook go into the screen, and the side that was in the screen, I put into the MacBook), and then it worked again.

I'll also list other possible solutions that worked for other people, maybe it works for you (it didn't for me):

1. Disconnect and Reconnect All Devices:

• Shut down your Mac and disconnect all peripheral devices, including your external monitor.

• Wait for about 5 minutes.

• Reconnect your external monitor and other devices, then start your Mac.

• This method has been effective for some users experiencing similar issues.  

2. Reset NVRAM/PRAM:

• Resetting the NVRAM/PRAM can sometimes resolve display-related problems.

• To do this, restart your Mac and hold down the Option, Command, P, and R keys simultaneously for about 20 seconds.

• Release the keys and allow your Mac to continue starting up.

• This process can help with various hardware-related issues.  

3. Detect Displays Manually:

• Go to the Apple menu and select “System Settings.”

• Click on “Displays” in the sidebar.

• Press and hold the Option key to reveal the “Detect Displays” button, then click it.

• This can prompt your Mac to recognize the external monitor.  

I hope one of these solutions works for you. Good luck!

This is what worked for me. I have a Mac Studio with three monitors. After the 15.3 update, only two monitors would show up. I have three different user accounts on my mac. 1) Administrator, 2) my main user account, 3) one for my son.

All three monitors came up in both my administrator user account and son’s user account. It was only my account where just two of the monitors were detected, which told me the problem was probably an errant file somewhere in my user account library.

I traced the file to library/preferences/byhost/apple.windowserver.displays.

I dragged this file to my desktop and restarted the mac. Upon rebooting, all three monitors successfully appeared.

I did have to reset the parameters of each monitor in the Display Preferences Panel eg arrangement, rotation (one of my monitors is vertical), screen size (eg 3840x2160), etc.

Hope this helps.

You sound desperate so I’ll report my answer so maybe you will see it.

This is what worked for me. I have a Mac Studio with three monitors. After the 15.3 update, only two monitors would show up. I have three different user accounts on my mac. 1) Administrator, 2) my main user account, 3) one for my son.

All three monitors came up in both my administrator user account and son’s user account. It was only my account where just two of the monitors were detected, which told me the problem was probably an errant file somewhere in my user account library.

I traced the file to library/preferences/byhost/apple.windowserver.displays.

I dragged this file to my desktop and restarted the mac. Upon rebooting, all three monitors successfully appeared.

I did have to reset the parameters of each monitor in the Display Preferences Panel eg arrangement, rotation (one of my monitors is vertical), screen size (eg 3840x2160), etc.

Hope this helps.