macOS Sequoia 15.3 wont let me detect my second display

I was able to get my second monitor working again by unplugging it, then deleting the windowserver.displays.#### plist.

Then I rebooted, waited for login prompt. Plugged the second display in at that point, then it came up.

Deleting the following two files and restarting resolved the problem for me (Sequoia 15.4.1):

1. Open "Terminal"
2. rm ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist
3. sudo rm /Library/Preferences/com.apple.windowserver.displays.plist

Confirmed that this is a software issue!! Took my M1 Pro to Apple and they said it was an issue with the logic board, so they replaced it. The logic board is pretty much the entire inside of the laptop. Brought it home, loaded a fresh copy of Sonoma (previous version) that was available in the logic board (hard drive) and boom - issue was fixed.

Then I loaded my backup from Time Machine, which had the latest copy of Sequoia, and the issue reappeared. This became clear that this is a software issue.

I re-erased my laptop and started from fresh with Sonoma, waiting for Apple to announce the bug has been resolved.

I have been told by an Apple consultant that it is most likely due to corrupted code from a previous MACos versions that has carried over. So, if I were to upgrade to Sequoia starting from a fresh copy of Sonoma, I may not have the issue. Currently, I just don’t want to take that chance of reverting back, as it severely affects my productivity.

<<I have a solution (I'm using 15.2 but should work in 15.3 too). After spending 40 minutes on the phone with apple, we figured out how to solve this. In the Finder, go to the "Go" menu, select "Go to folder". Type in "~/Library/Preferences" There is a preference file with the name that starts with "com.apple.windowserver.displays." then has a random long number, then ends in ".plist". Right click on this file, and "Move to Trash". Restart your computer. Done >>

This is beyond annoying. every time I wanna connect my external 4k monitor via thunderbolt it brings up a dialog as if this is a brand new display. I have to then choose to extend screen, change resolution, and move all windows from laptop screen to main display. EVERY TIME!! it completely takes away the work flow. In previous MacOS it just worked like windows. even deleting that com.apple.windowserver.displays file does not help. Apple fix this please

just started happening today. out of no where. i thought maybe i should upgrade macos to 15.5 but that didnt fix it. only one monitor works at a time, not both, although both light up, and both do work when im in startup options by holding power button when turning on, so its not a monitor or cable or usb problem, its a software glitch. Ridiculous apple where are your e2es???

i have 1 monitor plugged in with hdm and another with display port through a usb c dock. worked just fine till today.

just started happening today. out of no where. i thought maybe i should upgrade macos to 15.5 but that didnt fix it. only one monitor works at a time, not both, although both light up, and both do work when im in startup options by holding power button when turning on, so its not a monitor or cable or usb problem, its a software glitch. Ridiculous apple where are your e2es???

i have 1 monitor plugged in with hdm and another with display port through a usb c dock. worked just fine till today.

"the solution for me was very simple and strange"

Mac Mini M4 Pro. MacOS 15.5. 43" LG C4 TV x2 used as dual monitors. The LG TV used to extend the display started intermittently not being recognized after updating to 15.4.1, then was never recognized after updating to 15.5.

I tried everything after scouring the Internet without even temporary success. Ultimately I was limping along using the second monitor via ApplePlay at far less than its 4k resolution as the Mac Mini through Thunderbolt 5 port through USB C to HDMI adapter ("Cable Matters 48Gbps USB C to HDMI 2.1 Adapter for macOS, Supports 8K@60Hz / 4K@240Hz HDR, Thunderbolt 4 to HDMI 2.1 Adapter, Compatible with Thunderbolt 5 Laptops") through 10k HDMI 2.1 cable (10K 8K HDMI Cable 5-Pack 6.6FT, HDMI 2.1 Cable Bulk Ultra High Speed 48Gbps 8K@60Hz, 4K@120Hz Braided HDMI Cord eARC, HDR10, HDCP2.2&2.3) to the LG C4 TV.

I pulled the HDMI cable, flipped it, and then it worked again.

For about 1 minute, then the 2nd TV being used to extend the display was again not recognized by the MacMini.

I then pulled the HDMI cable only from the TV for a few seconds and after plugging the cable back into the TV the Mac Mini again recognize the 2nd TV and appropriately extended the display. (Previously detaching and reattaching the cable from the Mac Mini, switching ports on the Mac Mini, detaching and reattaching the adapter from the HDMI cable were without benefit.)

(Still working after 2 hours, so keeping fingers crossed!)

Before the latest update to 15.5, I was able to fix this problem by running:

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

However, this doesn't work any more. With the help of ChatGPT I used the search described elsewhere in this thread :

sudo find / -name "*windowserver*" 2>/dev/null | tee ~/Desktop/windowserver_files.txt

The suggestion from the AI was to run:

sudo rm -f /Library/Preferences/com.apple.windowserver.displays.plist \
  /System/Volumes/Data/Library/Preferences/com.apple.windowserver.displays.plist \
  ~/Library/Preferences/ByHost/com.apple.windowserver.displays*.plist \
  ~/Library/Containers/*/Data/Library/Preferences/ByHost/com.apple.windowserver.displays*.plist \

GPT: "Yes, it’s very likely macOS now references or prioritizes:

• /System/Volumes/Data/...
• User-scoped container directories (~/Library/Containers/...)
• Possibly multiple copies under specific ByHost UUIDs (try clearing all you find)."

Then shutdown:

sudo shutdown -r now

This worked for me. It looks like the displays.plist is now in a different location after the update, but I haven't bothered to work out exactly where yet. - This narrows it down a bit though. I hope this helps someone else, it's a really frustrating problem that has cost me a few days work over the last year.

For what it's worth. My external monitor stops working when my mac's battery reaches 100%. I don't know if it's the settings of the mac or the monitor. I have MacBook Pro M2 (Sequoia 15.5). External monitor worked fine until battery reached 100%. This was with USB-C cabel.

eugene-w wrote:

Didn't work for me though. The file keeps getting recreated after the restart!

I would expect the file to be regenerated, given that macOS uses it, and that it is not there for decoration.

As far as determining "was this a fix?", the question is not whether the file goes away, but whether the problems with detecting a second display do.

Having this same issue...

Macbook Air 13" 2025 (Mac16,12)
Sequioa 15.5 (24F74)
Dell Utrasharp U2722DE connected via USB-C 

I've tried deleting `com.apple.windowserver.displays.plist` but this doesnt seem to have any effect. The monitor works perfectly fine on my Macbook Air 2022 running Sonoma.

On the Sequia Macbook, If I shutdown and power cycle the monitor, sometimes when I then reboot the computer the monitor appears and works as expected, but as soon as the computer goes to sleep, or if I disconnect and later reconnect the monitor, it doesnt show up.

I've also updated the firmware on the Dell and installed Dell's display software on the MacBook 2025 to no avail.

Got hit with this upon upgrading from Sequoia 15.5 to 15.6. on an M1 iMac.

Second monitor running through a USB-C Thunderbolt to HDMI adapter refused to be recognized after the upgrade.

Logged in as a different user, no change

Did the system prefs->Displays->Hold Option Button-> auto-detect and it still wasn't recognized

Swapped USB-C Thunderbolt adapter to a different USB-C Thunderbolt port on the iMac, no change

Unplugged and reconnected all cables, no change

Deleted the relevant ~/Library/Preferences/ apple.windowserver...XXX file and rebooted, no change

What finally worked was to use a different USB-C Thunderbolt to HDMI adapter on the failed monitor, then the Mac suddenly recognized the monitor. After that, I swapped back to the original HDMI adapter that was not working and then "magically" the Mac was able to recognize the monitor again on the original HDMI adapter.

I have a feeling it has something to do with the USB subsystem and how the OS enumerates USB devices. I've seen this a lot with USB Printers attached to Macs where they will run fine for months/years and suddenly stop and the only way to get them recognized again is to plug them into a different USB Port.

This fixed it for me.

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

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.