Level 1

46 points

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

After updating my Mac Mini today to 12.3, my monitor now no longer displays an image via USB-C, just keeps saying on no signal on the monitor.

I have tried HDMI and same issue. The odd occasion it will display a picture but once I shutdown or restart the mac mini it does not display a picture. The mac is booting up. I have had to resort to connecting it to my old TV with HDMI connection.

This is so frustrating

I have tried resetting the SMC which had not appeared to work, also tried downgrading the displayport version from 1.4 to 1.2 (on the odd occasion I did get a picture) but that has not worked either.

Has anyone else having this issue?

The monitor I use is a BenQ SW270C.

This is really doing my head in and was wondering if anyone else has got a fix to this.

[Re-Titled by Moderator]

Mac mini, macOS 12.2

Posted on Mar 17, 2022 12:48 PM

Top-ranking reply

astn

Level 1

9 points

Posted on Mar 18, 2022 11:30 AM

So this is related to a previous long-standing bug with DisplayPort, which forced all of us to go into our monitor settings and switch from DP1.4 to DP1.2 so our external monitors would work. Apparently in "fixing" this bug, Apple decided that checking autonegotiation was redundant and the user needs to manually fix things.

The solution is to set your monitor to DP1.4. For a BenQ monitor, that is going to suck, because if you don't have a valid source input, it won't give you the display settings menu. You'll need to hook up a second computer to the monitor without macOS 12.3 so the monitor has a signal, then go into the menus (System -> Advanced -> DisplayPort) and switch back to DP 1.4. Your monitors will work.

I'm so happy to have had to troubleshoot this in the middle of a workday. It was problems like this that caused me to switch from Windows to Mac over twenty years ago.

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248 replies

abepan

Level 1

8 points

Jun 6, 2022 3:11 PM in response to cyeoman06

Hi - My external monitor Dell P2217H stopped working. I thought it was monitor issue, and went and bought new Samsung 'curved' display, since the Dell was from 2016..(found an excuse to get a new one). The New monitor a Samsung CRG5 (LC24RG50FQNXZA) started flickering as well. So I had to return it. Apple has to fix the external monitor issue.

aidammk

Level 1

8 points

Jul 22, 2022 6:48 AM in response to f1ght4fun

Hi, I have the same issue as well. I am trying to connect to a Lenovo ThinkVision monitor. I have a MacBook Pro (14-inch, 2021) with the M1 chip. Currently on Monterrey 12.5. I have a HDMI to usbC cable that I know works, because I have used it with an Asus monitor before. However, the Lenovo monitor only has DisplayPort, VGA and another type of port. So first I brought a display port to HDMI adaptor and tried it with my cable, and it didn't detect a signal. Then I tried contacting the HDMI directly and same thing. I have tried following the tutorials to detect displays on the Mac, but when I hold down the option key nothing happens, I can't even SEE the detect display option. Next, I tried lowering the FPS to 49,75Hz, as well as trying all different presets and again, nothing. I have even tried with my dongle, connecting the HDMI through to the dongle and then from there to the Mac, and again nothing is detected. I have tried 4 different cables now, and I know the monitor does not have an issue because it worked perfectly fine with my friend's ThinkPad laptop.

Please fix this ASAP, I have spent the past 3 days buying and returning cables, going through endless tutorials and I am losing my mind.

Sep 14, 2022 12:04 AM in response to mph206

There is another monitor related problem.

MacBook Air lid closed, external 5k monitor via TB HUB DisplayLink

Sabnzb running, it stops after some time and freezes. OSX freezes when trying to reboot. Forced reboot needed.

Can be reproduced.

But if the MB Air is open, so its display is on everything works, Sabnzb DLs fine, no more freezes.

The MB Air also reboots by itself from time to time, mainly when it sleeps. Switching the external monitor on and off seems to trigger these freezes.

Sim2019

Level 1

29 points

Sep 14, 2022 4:06 AM in response to cyeoman06

I just updated to Monterey 12.6 and my MacMini still actually detects my second monitor (DVI->USB-C adapter that works fine with Big Sur) but the monitor itself still says "No Signal".

This has been going on across multiple versions and for probably close to a year at this point!

Apple's working on it... right...

Sim2019

Level 1

29 points

Sep 21, 2022 6:38 AM in response to drinsamson

That doesn't work. I've tries so many things and nothing helps, it's a problem with Monterey that Apple apparently can't be bothered to fix, as it's been going on for more than a year by now (at least for me)!

Oct 19, 2022 11:12 AM in response to cyeoman06

i have the same problem with samsung m7 monitor , can't connect it any more with usb type c cable , i even bought new usb cable from apple, i thought my old cable is broken so now i spent 75 euros for a software issue :( .. only with hdmi which is only 30 fps .. it is really annoying as i do mush videos editing and the programs are quite slow...

hope they come with a new update yo fix this bug

mph206

Level 1

12 points

Dec 1, 2022 1:00 PM in response to cyeoman06

macOS 13 Ventura did NOT fix the problem. Way to go, Apple. Do you even care about us anymore? You know, the people who pay *WAY* more than top dollar for your sexy products that are supposed to "just work."

trin2255

Level 1

12 points

Dec 4, 2022 6:26 AM in response to mph206

Correct - the fact that this issue is still unsolved is a joke. My crappy old windows laptop has no problem using my displays / waking them from sleep, but my $2.5k MBP requires me to physically unplug and re-connect the TB3 cable every time I want to use the screens?

astn

Level 1

9 points

Mar 18, 2022 11:06 AM in response to cyeoman06

Same issue with dual BenQ PD3220U on a MBP16 (2019) over Thunderbolt-3.

tbirdvet

Level 6

17,096 points

Mar 20, 2022 4:23 PM in response to Catnip Toy

What is your monitor?

Mar 23, 2022 8:58 PM in response to cyeoman06

Same no signal/black screen issue but with an LG 34WK95U-W. After a 3 day fight, I got it to use HDMI, but it is at about half resolution. Nothing else works and everything is blocky.

Mar 24, 2022 1:22 AM in response to ingridau

As far as i notice, this issue is not getting much of a traction anywhere on outside portals, web resources or tech blogs.

What is the best way to bring Apple's attention to this !?

Mar 24, 2022 4:43 AM in response to f1ght4fun

I sent tip to 9to5Mac and MacRumors.

Latter already posted https://www.macrumors.com/2022/03/24/external-display-issues-reported-macos-12-3/

Mar 24, 2022 11:49 AM in response to f1ght4fun

Same issue here since Saturday March 19th. Using 2019 MacBook Pro. Work has been very hard this week without my second display. What dock station are you using that is working f1ght4fun

Mar 24, 2022 12:05 PM in response to spiderterp

I have the following dock station:

https://i-tec.pro/en/produkt/c31tripledockpd-2/

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