External Display Stopped Working After Updating to Catalina: What Now?

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macOS Big Sur is already in its public beta stage but a lot of Catalina bugs remain unsolved. For example, a lot of users reported that their external display stopped working after updating to Catalina.

According to reports, after upgrading to Catalina, the external monitor connected to the Mac has no display and the screen is all black. This usually happens when the monitor is connected via VGA cable, particularly those that are not from Apple. Some users have noted that connectors from Apple are able to work just fine.

Plugging and unplugging the external monitor does not work and it seems like macOS is not able to detect the screen. It doesn’t even show up under System Preferences > Displays.

This problem has made it inconvenient for Mac users who are used to having a multiple-display setup, such as designers and editors. If your external display is not working after Catalina update, this guide should have the answers that you need.

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For those who are experiencing black screen after updating to High Sierra, you should check out this article instead.

Why is External Display Not Working After Catalina Update

The main reason why some external displays are not working after Catalina update is that your Mac is failing to recognize the external monitor for some reason. It could be due to software incompatibility, since the operating system was newly updated. Or it is possible that the upgrade has corrupted something related to your external display.

In most cases, the operating system could not recognize the external display when it is connected using a non-Apple branded cable. However, there are also instances when a non-Apple cable was working fine. The trick here is to use a cable that is of good quality to make sure that your Mac will be able to recognize your device.

You should also not ignore the possibility of the presence of malware disrupting your Mac’s performance or corrupted files getting in the way of your Mac’s processes. The first step in troubleshooting any Mac problem is to understand what causes it, then formulating steps to resolve the problem. If you’re looking for the “External display not working after updating to Catalina” fix, then here is some advice for you. This error has affected the productivity of a lot of Mac users, especially those who require external monitors for everyday use.

How to Fix External Display Not Working After Updating to Catalina

If your external display stopped working after updating to Catalina, the first step in troubleshooting this error is to disconnect your monitor then unplug it before reconnecting it again.

Here are some basic troubleshooting steps you need to perform to quickly resolve this error:

  • Install all available updates on your Mac. Since you have upgraded your operating system, some of your device drivers might still be stuck with the old version, so you need to update them as well.
  • Perform some basic housekeeping, such as cleaning up your Mac using Mac repair app and running a scan to remove malware, if there are any.
  • You may also need to restart your computer before your Mac is able to recognize your external display.

To check if your Mac is able to detect your monitor, follow the steps below:

  • Click Start, then choose System Preferences.
  • Click on Displays.

You should be able see here all the displays connected to your Mac. If you don’t see your monitor and the screen remains black or blank, here are some of the solutions you can try.

Solution #1: Use a Different Cable.

If you’ve been using your cable for quite some time, it is possible that it has been damaged, causing your external display to not work properly. You can either try the cable on a different monitor or use a different and good quality cable to connect your monitor to your Mac.

Try different cable brands, use a cable from Apple if possible, since some users reported getting different results using different cables. It is a known fact how much of a stickler Apple is to its own brand, so it might be intentionally disregarding other cables from different manufacturers.

If you’re using an HDMI to connect your external monitor to your Mac, then you should check out some of our workarounds in this article.

Make sure that the cable is connected properly as well and that the ports are not damaged. It should not be connected loosely.

Solution #2: Edit Your Display Driver’s Privacy Settings.

By default, not all devices have permission to run on macOS. You need to give them permission to run one by one, to make sure that all your devices are working, including your external monitor.

To change your Privacy settings, follow the instructions below:

  1. Click on the Apple menu, then choose System Preferences.
  2. Click on Security & Privacy, then click on the Privacy tab.
  3. On the left panel of the window, scroll down to Screen Recording and click on it.
  4. On the right pane, tick off Enable the Display Drive.

This should allow your Mac to detect the external display.

Solution #3: Reset Your Mac’s Cache.

Since your Mac is running on a new operating system, you should try resetting your device’s cache to prevent issues like this from happening. The best way to do this is by booting into Safe Mode because it prevents third-party startup and login items from loading during boot up.

To boot into Safe Mode, do the steps here:

  1. Restart your Mac, then press the Shift key immediately after it powers on.
  2. When you see the login window, release the Shift key.
  3. If you’re using FileVault to encrypt your startup disk, you might need to sign in twice to unlock the disk and to log in to Finder.

Rebooting in Safe Mode deletes font cache, kernel cache, and system cache files. It also verifies your startup disk and fixes any directory issues, if necessary. So when your external display works in Safe Mode, it means that a third-party software is causing the error.

Solution #4: Change Your Resolution.

Another factor you might want to check out is the screen resolution. It is possible that the resolution you are using cannot be supported by your external monitor. To change the resolution:

  1. Go to Apple menu > System Preferences.
  2. Click on Display.
  3. Choose a different resolution, such as 1024 x 768 for a start.

Final Thoughts

If the above steps don’t fix your external display issue, you should consider downgrading to Mojave or another macOS version that worked for you. You can also try upgrading to Big Sur if your device is compatible with the latest macOS.

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