Anyone experiencing no signal output to the external monitor using USB-C after 12.3 upgrade

[fyuanster]

I just upgraded to 12.3 OS for my 2019 Macbook Pro 15 inches, and before the upgrade, it worked well with my LG 49 inches monitor by USB-C. However, after the upgrade tonight, it is saying that there is no signal to the monitor by USB-C. I can only use HDMI for the external monitor. Is there anyone having the same problem?

 

[whatthedeuce]

Yes, just registered for this site to complain about this issue.
However it's on a 2018 Mac Mini for me.
Was using USB-C to display port which worked fine before the update.
It's my only monitor and luckily I had an HDMI cable laying around so I can actually use my computer.
However the colours are completely wonky on HDMI compared to Display Port.

 

[nukethis]

Same issue for me on the 2018 MacMini. USB-C to DisplayPort adaptor to my LG Monitor. Zapped the PRAM and nothing. The "workaround" is that I use the blank screensaver(yeah I know, not the same thing). I hope that Apple fixes it... Anyone tried to downgrade a driver or a plist??

 

[PeteBurgh]

Yes, I also have this issue with a 2018 Mac mini - annoying!

Hopefully there is a x.x.1 fix coming...

 

[fyuanster]

Yes, just registered for this site to complain about this issue.
However it's on a 2018 Mac Mini for me.
Was using USB-C to display port which worked fine before the update.
It's my only monitor and luckily I had an HDMI cable laying around so I can actually use my computer.
However the colours are completely wonky on HDMI compared to Display Port.

What brand of monitor are you connecting?

 

[jjayr41]

Yup mine is broke as well using a LG 32in USBC monitor, was working great this morning before I updated....using m1pro MacBook Pro

 

[fyuanster]

Did anyone make a change of the displayport version on the monitor to let the monitor work again with USB-C? I tried, but had no luck.

 

[jjayr41]

Did anyone make a change of the displayport version on the monitor to let the monitor work again with USB-C? I tried, but had no luck.

I tried going from 1.4 to 1.2, unhook the usbc, reboot etc and back to 1.4 and no luck as well.

 

[748s]

Mac mini (6 core i5) with LG 32UL950 (display port V1.1), thunderbolt connection.
Monitor no longer works with thunderbolt connection after 12.3 update.
Monitor works with HDMI connection.
Thunderbolt cable tested on other thunderbolt devices, cable OK.

Disconnected monitor from power for 10 minutes, thunderbolt connection now working.
Odd.

 

[knoepflasdruecker]

After changing the OSD settings of my display (LG 27UN83A) from DP 1.4 to 1.2, it works again over USB-C. Many thanks for the hint!

 

[whatthedeuce]

What brand of monitor are you connecting?

Mine is a Samsung 28" 4k monitor.

 

[whatthedeuce]

After changing the OSD settings of my display (LG 27UN83A) from DP 1.4 to 1.2, it works again over USB-C. Many thanks for the hint!

Interesting. Mine only supports 1.1 and 1.2 and is on 1.2 but doesn't work(but used to work). Tried changing it to 1.1 but doesn't work for me.

 

[jjayr41]

Mac mini (6 core i5) with LG 32UL950 (display port V1.1), thunderbolt connection.
Monitor no longer works with thunderbolt connection after 12.3 update.
Monitor works with HDMI connection.
Thunderbolt cable tested on other thunderbolt devices, cable OK.

Disconnected monitor from power for 10 minutes, thunderbolt connection now working.
Odd.

Really odd, so I gave up last night and just unplugged the power to my LG monitor overnight. Shut down my MacBook Pro as well. This AM, I plugged in the usbc cable to monitor and fired up the Mac...it works now. It even works on 1.4 or 1.2 now....I don't know what changed but looked like my display settings on the Mac was reset as the backgrounds changed etc.

 

[Spanther]

My external monitor support is already flakey with the 14 M1 Pro via USB-C.

Guess I'm skipping this update until a fix is released.

 

[ResPublica]

My old 24" monitor refused to start after the 12.3 update (no LED-light)... I though it was broken or that there was something wrong with my power cable. In the end, it started to work again on its own. But since it happened right after the update, it might be related to what people describe here.

 

[Mygoodgomez]

Yep, same problem here. LG 27UK850-W monitor via USB-C cable I've used for years to 2018 Mac mini stopped working after upgrading to 12.3. Switching to HDMI gets things to work but colors are off.

 

[Akito]

Same for me. Purchased a brand new cable and LG 27BL85U-W a few days ago and it's been working fine via USBC. Right after the update? nothing. It will recognize the MacBook is plugged in, but will shut off about 10 seconds later and reconnect. Same thing, over and over. 2020 M1 MacBook Pro. Oh, HDMI works just fine, but dammit, I've been spoiled by USB-C. A fix would be pretty great right about now.

​

 

[bandits1]

Same or at least similar on a 2018 Mac Mini + LG 27UK650 connected via StarTech USB-C to DisplayPort cable. Startup and login goes fine, type in my password and then blank, nothing. I hear my external HDDs spinning up and my desktop setting up like normal, but I can't see anything. Tried restarting twice, reset PRAM and still nothing. Swapped out USB-C for HDMI, restarted one more time and, except having to reset the monitor scaling back to 2560 x 1440, everything was good again.

I'm okay running with HDMI, just pissed about the $27.99 I spent on that certified cable 3.5 years ago haha.

 

[Chancha]

iMac 2017. Have a type-C powered portable 15" 1080p display. Used to work 12.2 and before but with 12.3 it stops showing at all. The display OSD has no ability to change DisplayPort version, and then with just 1080p I doubt it is even using a modern DP version.

Oh well. Typical modern Apple software...

 

[fyuanster]

I connected the external monitor with my Macbook pro 2019 via DisplayPort now and it is working fine, and the USB c port is still not working. However, I still prefer using USB C as it can power the laptop with no use of the adapter coming with the it.

 

[LuminousFX]

I'm having this issue as well with my 2 displays on my Mac Mini. It would only output to one, via USB C, and not via the HDMI.

What worked for me was to disconnect the USB C display, it would boot up and display on the HDMI. After booting up, I would connect the USB-C display, and it's now outputting to both displays.

 

[nik1aa5]

I can confirm this issue connecting a Macbook Pro M1 13" (2020) via USB-C with an LG UltraFine 32UN880-B. Switching from DisplayPort version 1.4 to 1.2 fixed it for me.

 

[banitaba]

The same for me. 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 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 one 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.

 

[billbobbopeep]

Same on my M1 Max 16". LG32" 4k via usb-c. Changed display port from 1.4 to 1.2. No luck. Then as recommended above, simply unplugged the LG from power then plugged it back in and now it works

 

[fyuanster]

Upgraded OS to 12.3.1 just now, and the issue is still there.