Oliver Haslam·

macOS 12.3 Is Buggy When Using External Monitors Via USB-C And HDMI, Users Report

Apple’s macOS 12.3 update has been out for a little while now and it underwent a lengthy beta program, too. But that beta program doesn’t seem to have been able to iron out all of the issues with a growing number of people reporting that they are now suffering from problems relating to external monitors.

As MacRumors reports, people have been taking to various support forums across the internet to say that they are now having problems getting external monitors to work correctly after updating to macOS 12.3. Connections via USB-C and HDMI appear to be impacted.

One user wrote on the Apple Support forum:

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.

The issue is one that many people suffered from during the beta program, and we have to assume that Apple is aware that it has a problem. Hopefully a fix is released sooner rather than later, although MacRumors does point out that some have had success by making changes to the display protocol.

I’ve solved this problem (on 2022-03-15). On my monitor (LG LCD 27 27UN880-B IPS) I’ve went into settings, and I’ve lowered the DisplayPortVersion from the default v1.4 to v1.2. As soon as I’ve lowered the monitor’s DisplayPortVersion, my Mac with OS X 12.3 has started recognizing the second display correctly. It seems that the new OS X update has issues with a DisplayPortVersion 1.4 protocol (has faster data rate, faster refresh, and stream compression). Hope this helps.

Whether that works for everyone, however, is unknown. If you’re suffering from the same problem, know that you aren’t alone.

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