Using an external display with your Mac should be as easy as connecting the cable, but what if nothing shows up when you plug it in? In this tutorial, we’ll share all the fixes, tricks and techniques you can try to fix the external display not working issue in macOS.
Before we begin: are you sure everything’s connected correctly?
Let’s get the obvious out of the way first and make sure your external monitor and Mac are set up correctly. Follow the instructions here to make sure your external monitor is connected properly.
If you’ve followed the above instructions and your external display still isn’t working correctly, then you can try the following fixes:
1. Disconnect and reconnect
Let’s start with the simplest fix: turn it off and then turn it back on again! There are a few different techniques that you can try:
- Disconnect your adapter for 10 seconds.
- Reconnect the adapter.
If this doesn’t yield results, then:
- Disconnect your adapter.
- Power down your Mac.
- Reattach your adapter.
- Power up your Mac.
Some users have also reported positive results by switching their monitor on and off while also removing and reattaching the cable:
- Unplug the cable.
- Switch off your monitor.
- Reattach the cable.
- Switch on your external monitor.
Finally, if you’re using a MacBook, you can try disconnecting while also closing your Mac:
- Connect your Mac to the external monitor.
- Select the “Apple” log in your Mac’s menu bar.
- Click “Restart … ” and then immediately close your Mac’s lid.
2. Check your cables
Just because a cable looks connected doesn’t mean that it is connected securely. Even a slightly loose connection can prevent your Mac from recognizing the attached display.
If you’re experiencing issues with an external display, then it’s always worth detaching your cable and adapter and then re-attaching them firmly.
3. Don’t rely on battery power
If you’re running your MacBook from its internal battery, it may not have enough power to push pixels to an external monitor. Try attaching your MacBook to a power outlet to see whether this gives your laptop the juice it needs to power an external monitor.
4. Is your operating system up to date?
If your operating system is out-of-date, then you may be encountering an issue that’s already been addressed in a recent update, so you should check that you’re running the very latest version of macOS.
5. Let your Mac take a power nap
Similar to the “turn it off and back on again” method, you may be able to kickstart the connection by letting your Mac take a quick power nap:
1. Select the “Apple” icon in your Mac’s menu bar.
2. Select “Sleep.”
3. Wait a few minutes.
4. Wake your Mac by interacting with its trackpad, mouse or keyboard.
6. Remove any chained adapters
You can’t force a Mac to play nicely with an incompatible external display by chaining multiple adapters together!
If you have a chain of adapters, such as a Mini DisplayPort to DVI adapter chained to a DVI to HDMI adapter, you’ll need to replace this setup with a single, compatible adapter.
7. Check the brightness, contrast and resolution
Your Mac’s brightness, contrast or resolution settings can prevent your display from appearing on an external monitor.
To check that these display settings aren’t interfering with your external monitor:
- Select the “Apple” logo in your Mac’s menu bar.
- Navigate to “System Preferences -> Display.”
You can now look for any unusual or extreme settings or experiment by dragging the various sliders inside the “Display” menu.
You can also check that the brightness isn’t cranked down on your external display using the Ctrl + F2 keyboard shortcut.
8. Test with an alternative monitor
If your monitor is buggy, temperamental, or outright broken, then no amount of adjusting your Mac’s settings is going to fix the problem!
If you have access to a second external display, try attaching it to your Mac to see if it works. If yes, then this strongly indicates that the problem lies with your external monitor.
9. Check your graphics card and drivers
If you’re using a third-party graphics card, check that the card is seated fully in the Peripheral Component Interconnect (PCI) slot and that you have the very latest version of all the necessary drivers.
New versions of macOS sometimes include driver updates, so you should also check that you’re running the latest version of macOS.
10. Use macOS’ hidden Detect Displays feature
If macOS doesn’t recognize your external display automatically, you can try to force the connection using macOS’s Detect Displays feature:
1. Select the “Apple” logo in your Mac’s menu bar.
2. Navigate to “System Preferences -> Displays.”
3. Press and hold the Option key, and a “Detect Displays” button should appear.
4. Select “Detect Displays” to see whether macOS recognizes the attached display.
11. Resetting NVRAM: Wipe your non-volatile RAM
Non-volatile random-access memory (NVRAM) is a small amount of memory where macOS stores all the settings it needs to access quickly, including some settings related to the display.
If these settings become corrupted, then it can cause a range of technical issues, so resetting your NVRAM may resolve the issues you’re experiencing with your external monitor.
Before we begin, be aware that resetting NVRAM will also reset your system settings and preferences, so you may need to spend some time reapplying these settings following an NVRAM reset.
To reset NVRAM:
1. Shut down your Mac as normal.
2. Power up your Mac and immediately press the Option + Command + P + R keys.
3. Hold these keys until macOS restarts, then release them.
You’ve now successfully reset your Mac’s NVRAM and can check whether macOS is now playing nicely with your external display.
12. Try resetting macOS’s SMC
The System Management Controller (SMC) is a chip that controls many of your Mac’s physical components, so resetting SMC can resolve certain display-related issues.
To reset SMC:
1. Make sure your Mac is completely switched off.
2. Connect the power adapter.
3. Press and hold the Control + Shift + Option keys and the “Power” buttons for 10 seconds, then release all four keys at once.
4. Restart your Mac as normal.
13. Using 4K? Make sure your Mac is compatible!
If you’re using a 4K external display, then there’s no guarantee that your graphics card will be powerful enough to push all of those pixels to the 4K display.
Typically, most Macs produced after 2013 are capable of supporting this resolution, but if you’re unsure, then check your Mac’s technical specifications for more information.
14. Strange colors? Switch to a different profile
Perhaps you’ve managed to get your external display up and running, but the colors are noticeably different to how they appear on your Mac’s built-in screen.
Some external displays feature contrast and RGB (Red, Green, and Blue) buttons that you can use to tweak the display’s color profile.
If your external display doesn’t feature these buttons, then you can often fix color-related issues using macOS’s Display Calibrator Assistant:
1. Navigate to “System Preferences -> Displays.”
2. Select the “Color” tab.
3. Select “Calibrate … ” This will launch macOS’s Display Calibrator Assistant.
4. Follow the onscreen instructions to calibrate your display.
Alternatively, you can try out various color profiles to see whether any of these profiles are a better fit for your external display. To select a new profile, navigate to “System Preferences -> Displays – > Color,” then explore the various color profiles on the list.
Hopefully the above tips can help you resolve your external display not working in macOS issue. You may also want to fix your Mac not starting up issue, if that is why your external display doesn’t work. We also have an in-depth guide on how to set up a generic USB keyboard for your Macbook.