Fix macOS Monterey 12.5 Secondary Monitor Issue [Ventura Updated]

Last Updated on Jun 25, 2022

macOS Monterey 12.3 update was released for both Apple m1 Silicon and Intel Mac users. After macOS 12.3 update, several users noticed a lost of dual monitor functionality. We know that dual display support is how important for users who are working with heavy work, for example, graphics designers. Sometimes both display screens flicker on and off repeatedly when the second monitor is connected to the Thunderbolt port. Another issue with External Display is Resolutions.

Don’t bother, here I’m going to share with you important troubleshooting that maybe fix your Mac Monterey external monitor not working problem. on any mac, Apple’s Silicon M1-series, M1 Pro (MacBook Pro), M1 Max (MacBook Pro & Mac Studio), M1 ultra (Mac Studio), M2 chip of 2022 (MacBook Pro & MacBook Air) Or Intel chip Mac computer. Let’s follow it step-by-step.

Clue #0. Keep Automatic Graphics Switch off on your Mac laptop

Step #1. Click on Apple Logo from top Menu > Open System Preferences [On MacOS Ventura:- System Settings]


Step #2. Go to Battery

Step #3. Make Sure Automatic Graphics Switching Off if it is On, turns it off, and restart your computer.

It does work to increase Battery life, your Mac will automatically choose the best graphics mode based on your usage.

After restarting your computer, you can do toggle on for automatic graphics switching

This is work for me so I hope this worked for you like magic. Unfortunately, you are a Mac user, no luck fixing the external monitor using clue number zero, let’s continue for bottom solutions till the found exact result point of the macOS Monterey bug that really highly inconvenient.

MacBook Pro/Air Not Detecting External Monitor/Display

Clue #1. Disconnect the cable if Both screens flicker repeatedly 

Remove all cables from both computers and reconnect again. Next, connect both displays. If problems occurred due to broken cable or port then this will fix Monterey eternal monitor issue. In case of an issue is not related to the power cord, please go to the next workaround.

Note:- for those guys who have a second display cable not working – they should try a different cable, Or try to use Thunderbolt 4, Thunderbolt 3, or USB-C port adapter.

But in this Monterey 12.3 Update, the External monitor caused the issue with the USB-C Cable connection between your Mac and External Display. Wait for the Next update or Try the alternate solution as given below for now.

Clue #2.  Display showing blank screen or not detected blurry on your Mac

Check the given below setting on your display;

1 – Detect your display

Go to the Apple menu – choose sleep – you Mac will get to sleep mode– after a few seconds press on the mouse or any key of the keyboard to wake your Mac machine. 

sleep mode settings on mac

With this, you can see an image of the connected external display

2- Make Sure Mirror Displays is Enabled 

Go to Apple menu – choose system preferences– go to displays – click on click on arrangement section – make sure Mirror displays is enabled. 


On MacOS Ventura: Go to the Apple logoSystem Settings > Displays > Find the Mirror displays settings.

Note: – For Apple Silicon M1 Mac– Only Restart works as an SMC and RPAM & NVARM.

3- MacOS Monterey display resolution problem

Plugging and unplugging an external monitor is easy with your Mac to stop mirroring. But the cause is resolution, Mac display resolution got affected and Has to change all time from System settings.

Here’s the solution for a problem like this, Setup optimation for External display from Display settings. Assign both Displays for Main and Secondary display one by one.

macOS Monterey:-

  1. Go to the Apple Logo from the top Mac menu > System Preferences.
  2. Click on Display > Display Settings.
  3. Mac display use as Main Display and External display Use as Extended display.change-display-settings-and-set-a-primary
  4. Also, check the Resolution option for both the display: “Default for Display”, “Scaled”. change-display-settings-for-external-monitor
  5. Tap on done to apple the change. Now, while you plug or unplug the device the resolution will be set according to the configuration that you set up earlier. That’s it.

On MacOS Ventura:-

Step 1:- Go to the Apple Logo from top menu > System Settings.

Step 2:- Now, Click on Displays > See Display Settings for External display.

3- Reset SMC on your Mac

the SMC has a role to control thermal and power management on Mac machines. Resetting SMC on your Mac, it boost your Mac speed and resolves some hard issue on your Mac. So to fix the external monitor or display not working, let’s get here reset SMC on Mac computer. [guide for only intel mac users]


Skip this step for M1 Mac [Just need Restart], here’s a complete guide to reset PRAM and NVRAM on an Apple mac computer.

5- Restart your Mac in Safe mode

would like to go with a safe mode solution to fix the external display not detecting issues after the monetary update. follow how to restart your mac in safe mode.

5.2- Keep Your Mac Software Upto Date

You should check your mac software update, recently the Mac software update is macOS 12.3, please install it and try to connect the second monitor. if your mac is unable to install the latest macOS, please refer to this solution that fix cannot install the latest macOS 12.

6- Re-install macOS

A complete guide for re-install macOS Monterey.

if none of the above solutions are suited to fix your mac’s latest installed Monterey 12 update, without west of time, I suggest you should go back to the previous version of macOS. if you don’t have an emergency and can hold till the next three to four weeks then wait for the upcoming macOS udpate.

7- Downgrade macOS 12.XX to macOS 12 Monterey or Ventura

here’s a full informative guide that will teach you how to go back to previous macOS firmware from the latest one. For Downgrade macOS Ventura to Monterey.

you guys, don’t miss to leave your feedback, and share with us what clue worked for your Mac to detect external monitor on macOS Monterey.

we are happy to help you, submit this Form, if your solution is not covered in this article.

HowtoiSolve Staff

Jaysukh Patel is the founder of howtoisolve. Also self Professional Developer, Techno lover mainly for iPhone, iPad, iPod Touch and iOS, Jaysukh is one of responsible person in his family. Contact On: [OR]

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