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

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.

I have an iMac (Retina 5K, 27-inch, 2020) and I purchased recently a portable monitor Lepow Z1 USB-C and it was working properly with the previous version of macOS. As soon as I upgraded to 12.3, the monitor could not be detected and it shows the "No signal" error. I did all the jobs that were found on the Internet and Apple website like unplugging and plugging again Clearing NVRAM, connecting on the time of turning on, logging in a safe mode, changing the USB-C cable, using the Mac Original Thunderbolt 3 cable and so many other unusual works that somebody said like changing the direction of the cable and so, but no change. I already talked 2 times with Mac support and they still could not fix the problem. The same monitor with the same cable is working with my MacBook which is under the previous macOS version.

It works with some of the USB-C to HDMI adapters but not all. It works with a cheap one which is a no-name random USB-C HDMI adapter but I have another that I purchased more expensive but doesn't work with that.

I just recommend downgrading if you just upgrade it till the moment that a real solution will be there.

Does anyone have a solution?

Mac Mini (2018) with LG 32" 4K monitor. Worked perfectly since the computer and monitor were new. I upgrade to 12.3 and boom, all the same problems in this thread.

Apple, IT'S BEEN 10 DAYS! FIX THIS! It's a Mac Mini. I don't have an internal display. How am I supposed to even do a software update if I can't log in because the display just goes straight to black after booting?!

I have tried several of the workarounds listed here that will work sometimes or for a couple of restarts. Very troublesome and disrupts my workflow considerably.

Come on Apple!

What ever happened to "It just works!"?

Same problem here. Two acer nitro vg240Y and 2018 Mac mini i5 32g ram 512g ssd and 2013 Mac Pro 4core d300 32g ram 512g ssd.

Both Macs updated to 12.3 and I’m getting all sorts of problems here. Anything from. No cable plugged in and no signal to everything working and one sleep cycle ruining everything.

I have spent past week trying absolutely everything including an array of different cables, screen, settings and everywhere the result is absolutely inconsistent. It is easier to deal with a single monitor setup. Dual monitor works way worse and less predictable. Can’t wait for the fix or possibly gonna roll back to Big Sur… Can’t imagine how disappointed someone would be with a Mac studio since you can’t roll that one back…

Same issue. “No signal found” on monitors, and MacBook doesn’t detect external displays either.

16” intel MacBook Pro & two Dell Ultrasharp 4K monitors each connected directly via USB C cables, no dock

I updated to 12.3 last week WHILE connected to my 2x monitors in clamshell, I had no monitor issue booting into 12.3 for the very first time. But after unplugging for the weekend, shutting down and powering up, and then plugging in today - now I get the “no signal found”.

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.

Same issue. Updated my work MBP 2021 to Monterey, and my external Dell 4K monitor no longer works via DisplayPort. It is absolutely incredible that such a bug (or is it a "feature") has not been addressed.

I wish I could change the DisplayPort version but I use a portable monitor that does not have these settings. Apple, I have now been working for 11 days with no second display and it is incredibly dysfunctional and frustrating that such a simple capability is so broken. I need my second display to work. Please please fix this.

There are a decent amount of posts talking about moving from 1.4 to 1.2 or 1.1 DisplayPort. My monitor only has 1.1 and 1.2 and switching between those doesn't make a difference. I get the same issue where the computer randomly doesn't recognize the display.

The same issue happened to me yesterday as I updated to Monterey v12.3, after the upgrade I lost video to the screen using the DisplayPort on a MAC mini (2018). The monitor I am using is a dell s2721dgf. I never had an issue with the DisplayPort until I did the upgrade. I was able to get the monitor to work using HDMI instead of DisplayPort. I prefer to use DisplayPort over HDMI, hopefully there is a solution to this problem soon.

I am using a USBC thunderbolt to DisplayPort cable which was highly recommended to use with the Mac mini.

Hey Apple, what's wrong with this once great company?

Same Issue here. MBP 16“, Intel, Late 2019.

hp U32 4k HDR Monitor. USB-C connection.

I need the stuff to work and not to have fun. I have been massively disabled in my work for almost three weeks. When will this error finally be corrected?

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

With 12.2, I ran my Karaoke night with two HDMI cords plugged into my USB bus, as I have been doing since before I got my M1 iMac. I went to run it with 12.3, and now my Mac does not give me any options in System Preferences/Displays. Well, now I can move my mouse to my iPad, but that's not what I need. I need my Mac to see my external displays!

Same issue with BenQ EW3270U and Mac mini 2018 (intel). Two solutions (after 2 useless helpdesk-sessions and 2 re-installations):

1st Changing from USB-C to HDMI. Works instandly, but no sound from monitor.

2nd Turning the USB-C plug 180°. Works perfect.