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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

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248 replies

Mar 30, 2022 2:18 PM in response to cyeoman06

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.

Mar 31, 2022 5:57 AM in response to Kyoha

Maybe a workaround, but not for free. Today bought a ANKER PowerExpand+ 7-in-1 USB-C PD Media Hub EUR 31,99 from Amazon.

It works with HDMI cable. Max resolution 3200x1800. Not the best, but it's more comfortable to work.

Nevertheless, I expect Apple to fix this bug immediately. If this takes a long time, the question arises of clarifying this in court.

Unnecessary investment in cables and adapters, massive limitations in daily work.


Mar 31, 2022 7:37 AM in response to cyeoman06

Continue testing everything I have. Unfortunately do not have a single monitor that supports DP1.4, only DP1.1 and DP1.2. Absolutely useless now. Both Mac pro 2013 and Mac mini 2018 are now paperweight. Now thinking on how I can roll them back to big sur or at least 12.2.1…


Absolutely disappointed! Keeping all the rest of our macs in the office without updates for now.


[Edited by Moderator]

Apr 1, 2022 3:21 AM in response to cyeoman06

Now solved with Apple Support.

Update 12.3.1 did not solve it for me.

No black screen, but frozen screen.


We had to remove 2 specific prefs files, reboot the computer and now ok.

Taken steps:

In your SSD or HD:  system library - preferences - look for com.apple.windowserver.plist - remove it

Also on your user library -  via hidden key press: go to the Finder - click  in top menu on Go - press key option on the keyboard - choose Library - Preferences - ByHost - com.apple.windowserver.plist - remove it

Advice: contact Apple Support if you are not easy with this to execute on your own.

Reboot - it should now be ok

In my case this solved it.

I assume there will be another minor Monterey update because of this

Apr 3, 2022 11:52 PM in response to cyeoman06

My Mac mini ist connected to a TV via HDMI. After upgrading from 12.3 to 12.3.1 my computer does not recognise the TV correctly, i.e. I have a picture but the color profile simply says "Monitor" and I am no longer able to switch the sound output to the TV set. Seems that the HDMI handshake is broken somehow. Very annoying.

Apr 4, 2022 3:38 AM in response to cyeoman06

I just installed 12.3.1. on my Mac Mini 2020. The changelog only mentions the Mac Mini 2018 and my second monitor that's connected via a DVI -> USB-C adapter still says "No Signal" after a restart, even though Monterey still lists it in the "Display" settings and I can still move the mouse cursor to it. My main HDMI->HDMI monitor is still working fine. Ffs Apple, get your s...tuff together!

Apr 8, 2022 8:44 AM in response to Devbkk7

I had a very helpful & competent APPLE 🍎 supporter doing this together with me with a lot of patienece, the screen came back after the process described by you. I said I don’t believe it 😵And see, it went to sleep after about 2‘. He asked me if I would prefer to work wit a supervisor or wait for an update…. I chose the later and hope it gets solved with 12.3.2🙏🏻 However he tried everything. In 🍎 I trust. Thanks for the time invested 🙏🏻

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

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