macOS Sequoia 15.3 wont let me detect my second display

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.

I'm having the same issue as everyone else. I updated to Sequoia 15.4, and my second external display (a dell) only shows "Choose to Mirror or Extend Display from the menu". I can't make any changes to the display which is apparently unrecognized by the menu.

I've tried everything except delete the com.apple.windowserver file, because I can't find that file anywhere on my computer. It isn't in the /library/preferences/ folder or anywhere else. Am I missing something?

Everything worked before the update. Thanks.

MacBook Pro M3 Pro + 2 external monitors working! (ASUS + Alienware, no DisplayLink)

Hey folks,

Just wanted to drop this here in case it helps someone. I finally got two external monitors working on my M3 Pro MacBook Pro without using DisplayLink or any weird docks.

Setup:

• ASUS XG27UCS over USB-C → DisplayPort
• Alienware AW3225QF over HDMI 2.1
• Internal display off

At first, I could only get one external display working at a time. But after a bunch of messing around, here’s what worked:

1. Plugged in an old FullHD Dell as one of the displays.
2. Used BetterDisplay to drop the ASUS down to 2560x1140 @ 60Hz.
3. Swapped the Dell for the Alienware — boom, both displays working.
4. Then I bumped the ASUS back up to 120Hz, and it still worked.

So now I’ve got:

• ASUS @ 2560x1140 120Hz
• Alienware @ 3840x2160 120Hz

No crashes, no flickering, totally stable. Been using it like this for work and it’s solid.

I think the issue was just hitting the bandwidth limit on the M3 Pro. The ASUS and Alienware have different native refresh rates and resolutions, so I guess the system was choking until I “eased in” the config with a lower load.

Hope this helps someone else struggling with dual displays on these new chips. Let me know if you want more detail.

Cheers!

For anyone who thinks they've fixed this by doing X, Y or Z:

Wait a few days before coming to any conclusions. The thread is full of people saying they have fixed it by doing something, only to return shortly afterwards saying the problem has returned.

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

That terminal command "worked" for me, I think.

However, just in case it's relevant, here's what I also did:

1. Previously, I had rebooted my laptop about 15 times as I tried various "solutions,"
2. I complained to co-workers who use Linux and Windows machines while explaining why I couldn't focus on my tasks presently,
3. In Displays preferences, I hit "Detect Displays" roughly 30 times (no feedback; the button might be a "hello world" PoC button hooked up to nothing),
4. I previously deleted numerous com.apple.windowserver.<hash>.plist files, emptied trash repeatedly,
5. As my body language became slightly more aggressive and fed up, I made eye contact with other co-workers who were happily using external monitors on hardware that was a couple thousand dollars cheaper,
6. After running the above command, I rebooted while holding down Option+Command+P+R just in case that did anything (no feedback from UI; it may be another placebo),
7. Finally, during the last reboot, I was actively focusing on and pondering if using Macs is really worth the constant deprecations, extra costs for hardware that no longer "just works," $100+ dongles, and the consistently declining UX.

Something in all that worked.

My fix was surprisingly simple, that is I switched from a miniDisplayPort-USBC Cable to a HDMI-USBC cable.

Tried all the software fixes discussed to no avail, but this did the trick.

While upgrading from Sequoia 15.5 to 15.6. on an M4 Pro Mac Mini with two LG TVs for monitors with one attached via HDMI and the other via Thunderbolt 5 port with converter to HDMI, the install stopped for several hours. I detached the monitor connected via the Thunderbolt 5 port and the install resumed. I think this also suggests a USB subsystem problem in MacOS 15. (Apple please fix this!)

Fear ye not, oh ye of little faith.

Each case a case, HOWEVER! We all want the shortest path to resolving our very pain:

1. Process Killing/Restarting commands:

sudo pkill -9 WindowServer
sudo pkill -9 usbd
sudo launchctl unload /System/Library/LaunchDaemons/com.apple.windowserver.plist 2>/dev/null; sudo launchctl load /System/Library/LaunchDaemons/com.apple.windowserver.plist

2. System Reset Commands:

sudo nvram -c
sudo pmset -a powernap 0
sudo pmset -a sleep 0

3. Preferense Reset commands:

sudo nvram -c
sudo pmset -a powernap 0
sudo pmset -a sleep 0

4. RESTART YOUR LAPTOP

sudo shutdown -r now

Hi, I have macOS Sequoia 15.6 and I faced the same issue of mac not detecting my second display. I had Display Port in my ASUS monitor connected to Display Port in the dock which is connected to mac using USB-C. I was going through one of the answers were someone tried connecting HDMI cable and disconnected DVI, then the second display started to work. In my case, I tried the same (meaning added HDMI and removed Display port) but did not work. After couple of tries, I have added the Display Port cable as well and second monitor started to function using the display port. Sounds strange, no logical explanation, but it works. Currently both HDMI and Display Port cables are connected from the monitor to the docking stations. Thought of sharing in this thread as this worked for me. Thanks to everyone who tried and posted multiple suggestions.

After accidentally disconnecting my external display via Screen Sharing, the monitor completely stopped being detected in macOS (it didn’t even appear in system_profiler). Macbook M4 Air, Sequoia 15.6

Checking cables, ports, and resetting NVRAM/SMC didn’t help.

What fixed it:

Open Terminal and run:

sudo rm /Library/Preferences/com.apple.windowserver.displays.plist

then restart your Mac. After restarting all worked again!

Note: This deletes the global display configuration. macOS will recreate it at startup.

Hopefully this saves someone time and nerves 😊

For me what helped was this:

• Disconnect monitor
• Run these commands both:

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

• Reboot
• Login
• Reconnect

I can't believe after days of trying (with no success) all the fixes people posted on reddit and here, this is what worked for me...TURNING THE CABLE AROUND. Anyways, thank you so much.

I’m using a Kamvas Pro 16 (2.5K). It doesn’t show up under Displays in Sequoia, although the tablet itself is still functioning. It works perfectly fine on my other macbook with Sonoma. I really rely on this for work, so the issue is very frustrating.

I have upgraded to 15.6.1. I have just recently discovered this issue because I had my work PC plugged into my 2 external monitors and my Mac just plugged into one. But I switched and went down the rabbit hole and found out this hasn't been fixed in a long time. I have both monitors up, but they won't extend. They are only mirrored. And when I go to displays, only one monitor shows up as available so I have no idea what's happening. I've switched docks, cords, restarted, gotten rid of the plist. I'm not going back to Sonoma. Apple needs to fix this.

When I plug the PC in, both monitors work just fine.

The sleep mode with later systems gave a multitude of users different problems. Do not sleep the Mac. If you leave it for a length of time shut it down as well as overnight.

There are the settings I use but you can change the top two to suit your needs: