M4 MBA cannot connect external monitor without deleting preferences

[drapestar]

Hi, I just bought a new M4 MBA and when I go to connect it to my Dell UltraWide 34" via USB-C, nothing happens -- no charging, and no display. The only way around this I've found is to delete the "com.apple.windowserver.displays.plist" preference file and restart the machine every time I connect it to the monitor. This isn't a sustainable or fun solution to do something my M1 MBA had no problem doing :/

The machine came with macOS 15.3 out of the box, and the problem didn't start until I updated to macOS 15.6.1

Any advice or suggestion? Or is this a "it'll get fixed in the next update" kind of problem?
Thank you!

 

[!!!]

Contact Apple support.

Any advice or suggestion? Or is this a "it'll get fixed in the next update" kind of problem?

This is unlikely, but the possibility increases the more people complain to support about it.

 

[drapestar]

Contact Apple support.

This is unlikely, but the possibility increases the more people complain to support about it.

Do you think it’s my specific monitor? It seems like such a bizarre problem to have this day and age and seems so clearly tied to the OS upgrade. What a silly and frustrating issue to have.

 

[Fishrrman]

Just some random thoughts...

Are you using a USBc-to-displayport cable?
Does the display have other input formats?
Such as HDMI, or even DVI?
Is there any other way to connect MBair to the display, OTHER THAN USBc?
---
What happens if you...
a. disconnect the display from the USBc port
b. boot the MBair
c. THEN RE-connect the display?
Does it "come back" or do you still have to delete the plist file?
(yes, I realize it's a pain to disconnect/re-connect, but might be easier than deleting the file each time you boot)
---
Do you have a spare SSD around?
If so, you might consider enrolling in the Apple beta test program, then download and install the beta version of Tahoe.
Then... see if the problem persists there, or if it's corrected?
---
Do you have A DIFFERENT DISPLAY with which you could try the MBair?
Do other displays exhibit the same problem, or does the problem disappear?
---
Do you have an Apple Store anywhere close?
If so, and if nothing else works, perhaps they could "downgrade you" back to something earlier than 15.6.1 ...

 

[drapestar]

Thank you for your response, Fisherman!

I am using USB-C to USB-C as provided by Dell. This same cable worked seamlessly for my old M1 MBA and old work M1 Pro MBP.

There's HDMI and a DisplayPort connection on this monitor, but I don't have a USB-C connection. I do have an Anker USB-C hub with HDMI port, and I just tried connecting my HDMI - DisplayPort cable and am not receiving a signal that way, either. I think direct USB-C and this Anker hub are the only ways I have to connect to the monitor.

Going through your troubleshooting suggestions:

1. disconnect, boot, then re-connect method: monitor says there is no signal.

The only SSD I have is full of my wedding videos and pictures so I am probably not going to mess with it for beta purposes (probably no harm to do so, but not wanting to risk it)

I do have another display, but prefer this one substantially. I will test that one later and see if there's a change.

Thanks again for your thoughtful suggestions here!

 

[drapestar]

Well, for anyone who happens upon this same problem... I have no idea what I did besides delete the preference file a bunch of times, but the issue has resolved itself and I am able to connect to my external monitor now without needing to delete the file and restart. It's magic...?