Hello,
I have an old iMac 2012 that I was using as second monitor for my a MacBook Pro 2016 using thunderbolt to usb-c adapter and works great. Now I recently purchased a new MacBook Pro 2020 as well as the Thunderbolt 3 adapter. Once I did the connections, the MacBook doesn’t recognize the second display.
Please help
2020 MacBooks no longer support Target Display as a source.
From Use your iMac as a display with target display mode - Apple Support
You can connect any of these older iMac models to another Mac from 2019 or earlier for use as an external display.
Hi, Eliqueii.
Welcome to the Apple Support Communities. We’re glad you decided to reach out about not being able to use your new MacBook Pro and iMac together. It sounds like you’re attempting to connect the iMac to your MacBook Pro using Target Display Mode with the intent to use the iMac as your secondary display, but the MacBook isn’t recognizing the display.
You mentioned that you purchased the Thunderbolt 3 adapter. Is the the adapter that you’re using?
About the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter - Apple Support
If it is, try these steps:
Leave both of your computers plugged in and restart the iMac. Once the iMac has been restarted, restart your MacBook Pro. After both computers are fully powered up, unplug the adapter from your MacBook Pro and plug it back in. Press Command + F2 on the iMac to see if it works.
You’ll also want to take note of the requirements for Target Display Mode outlined in this article:
Use your iMac as a display with target display mode - Apple Support
Note that your iMac has to stay on macOS High Sierra or earlier for it to work. If you’ve upgraded to macOS Mojave or Catalina on your iMac Target Display Mode is no longer supported.
All our best.
Using iMac 2012 as second monitor to MacBook Pro 2020
