Monterey 12.3.1 External Monitor/Display Issue - No Longer Outputting Signal

https://www.macworld.com/article/628371/macos-monterey-12-3-1-big-fixes-security-updates.html

there seems to be a patch today - hope it helps everyone and not only mac mini 2018 ....

try 12.3.1 it works for many BUT for a lot NOT

In my case with a vintage DELL monitor, using the other monitor plug and buyung a 8 usd adapter to hook it into my mac mini m1 solved the problem.

macOS 13.1 may have fixed the problem. At least, I haven't encountered it once since installing this update. Has anyone else had this bug rear its ugly head with 13.1?

Just chiming in. MacBook Air M1 12.3 made my external display no longer be detected. I am pretty unhappy, and I need this basic function for my job.

After a few frustrated google searches and many attempts to fix, I am still stuck. Please fix Apple.

NVM. I retract this statement. When I got back in this morning it was back to no external display (thanks Apple! Happy Monday!)

This needs fixing urgently, obviously. and no, I'm not buying an Apple display.

Similar problem with Mac mini (2018) + LG 34BL850 with USB-C.

After the upgrade, things work from the moment Mac mini boots until the first standby. When mac switches to standby and awakes from it, the display doesn't get a signal, hard restart is needed.

After the hard restart, there is a diagnostic window about segmentation fault: "window server Termination Reason: Namespace SIGNAL, Code 11 Segmentation fault: 11".

I have the same issue with my iMac when I upgraded it to macOS 12.3 from that time my external USB-C monitor is not detected and displayed a "No Signal" error. while it works with some of the USB-C to HDMI adaptors.

The same monitor and the same USB-C cable is working properly on my MacBook that its macOS is not upgraded.

Another interesting thing is that even some of the USB-C to HDMI adapters are not also working with my upgraded computer while those are working with my MacBook with a downer macOS version!

I already check all the things on the apple checklist and had talked 3 times with the apple support.

If somebody has a solution please let me know.

Same issue here with a MacBook Pro 13-inch and an external monitor from LG which is connected with DisplayPort. Since the update to 12.3 there was no signal.

I tried different solutions but they laat one was working for me to move from DisplayPort to HDMI

Same thing here!

I just bought a MAC STUDIO M1 MAX and when I tried to use my Samsung Odyssey G9 with USB-C -> DisplayPort cable, I got no image at all!

I tried to switch the monitor from 1.4 to 1.2 and 1.1 displayport versions and it still not recognizing the monitor. I bought 2 other different cables and the problem persists!

The only way to use the monitor is using HDMI, with this HORRIBLE resolution!

My old mac is with bug sur was working pretty fine with this monitor!

So the conclusion is that Monterey can't use displayports at all!

I'm wondering how a multi-billion company releases an OS with that limitation! What a shame!

I'll probably going to return my MAC STUDIO and, if one day they fix that s*, maybe I buy it back again.

Having same issues with a MacBook Pro (16-inch, 2019, 8-Core Intel Core i9) and a Dell monitor model U3818DW, connected through usb-c (this monitor uses dp v1.2 protocol through usb-c).

After some hours of usage, the monitor randomly disconnects and says "No signal", disconnecting the cable and reconnecting DOES NOT WORK. I need to turn the monitor off and on. It reconnects, but keeps losing signal each 5 minutes or so until I turn the Macbook off, let it cool down a bit, and then turn it back on so I can use it again for a couple hours before happening again.

If you get a "no cable plugged in" error, then your connection might really be wonky. With my DVI monitor (using a DVI->USB-C adapter) I only get that error if one side actually isn't connected properly, otherwise it's always "No Signal", so basically the monitor knows that it's connected but doesn't receive an image from my Mac Mini.

Because i had an old Apple Thunderbold Display still around.

Bought  the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter … this works on the Intel Mini.

Well it’s better then a black screen on my 32 “ LG etc

Having this issue as well. Tried multiple adapters... no success. It will connect temporarily to an external display, but after about 5-7 seconds it goes blank. I connect primarily to a Black Magic Atem Mini for work purposes, but also have an LG ultrawide display that this happens with. I have not tried using my OWC Pro Dock yet which will go Thunderbolt 3 to DisplayPort... but for sure all USB-C to HDMI options are not working.

Perhaps some steps in above article need a review

or performed. However there are no guarantees in

this matter. Like 'volunteers' here, are fellow users.

Monitors may have a need for updated drivers(?)

Does the maker's website show anything new?

Sections, as: install after repairing startup disk; using

macOS recovery; Safe mode; erase & reinstall; &/or

perform basic troubleshoot/repairs.

Always good to have good backups, & maybe clones.

..I'm going offline again; to try & resolve local matters..