macOS Catalina upgrade, released recently has seen its fair share of technical glitches. One such issue centers on using external displays with macOS Catalina. Several users have found that when they connect their MacBook to an external display, the screen simply turns black on the display and eventually shuts off.
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Another issue reported by some users is that the external display blinks randomly when connected to the MacBook running macOS Catalina.
Black Screen on External Display with macOS Catalina
It appears that in order to tackle the black screen issue on the external display, you have to change a ‘Privacy’ setting.
- Click on > System Preferences
- Click on Security & Privacy
- Choose Screen Recording on the left panel of the screen
- Enable the Display Driver here in these privacy settings
This should take care of the black screen issue on the external display.
If that didn’t help, try resetting your Mac’s cache by starting up in Safe mode
- Restart your Mac and immediately press the SHIFT KEY
- The Apple logo appears on your display
- Release the Shift key when you see the login window
- To exit safe mode, restart your Mac without pressing any keys during startup
- If your startup disk is encrypted with FileVault, you might need to log in twice: once to unlock the startup disk and again to log in to Finder
Safe mode performs certain checks and prevents startup items and login items from opening automatically
Starting your Mac in safe mode does the following:
- Deletes font caches, kernel cache, and other system cache files
- Verifies your startup disk
- Repairs any directory issues, if possible
- Loads only required kernel extensions
- Disables user-installed fonts
In the case of external display issues with your Mac, it’s also a good idea to check out the resolution and Refresh rate parameters.
Click on > System Preferences > Display and use 1024×768 as a start.
If you are using an adapter in your external display setup that is connected to your displays via HDMI/USB-C connectors, sometimes removing all the cables including HDMI, USB-C and ethernet cable, etc and then reconnecting everything can overcome this issue.
You would be surprised how removing all the cables and reconnecting everything can sometimes clear up any external display issues you may be experiencing.
For details around setup and troubleshooting external devices, you can read through the suggestions in this Apple white paper.
Do you use USB-C to HDMI?
If you are using a TV with HDMI cable as an external device, there have been some discussions around this issue on the Apple Support forum. You may have to use a USB-C to HDMI Cable as a workaround. If you use a USB-C to HDMI adapter already, it may be too old. Try borrowing or purchasing a new(er) USB-C to HDMI cable and see if that works.
For the external display screen flickering issue, we haven’t seen any particular settings changes that could cause this.
General troubleshooting tips would include checking the following:
- Connect your Power cord to your MacBook when using the external display
- Check and make sure that the external display’s power cable is connected properly to the source and is not loose
- If you are using a display hub, bypass it and try connecting your monitor directly to your Mac
- Restart your Mac with the display connected and see if that helps with the flickering issue
We hope that you found this short article helpful in finding solutions to your problems with External Displays and macOS Catalina. If you found a tip that helped you resolve the screen blinking issue on macOS Catalina, we would love to hear from you.
Obsessed with tech since the early arrival of A/UX on Apple, Sudz (SK) is responsible for the editorial direction of AppleToolBox. He is based out of Los Angeles, CA.
Sudz specializes in covering all things macOS, having reviewed dozens of OS X and macOS developments over the years.
In a former life, Sudz worked helping Fortune 100 companies with their technology and business transformation aspirations.