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iw12 Author

Level 1

30 points

Target Display Mode not working 2020 MacBook Pro (Catalina)

Target display mode not working, I want to set up an old iMac (mid-2011 running High Sierra) as an external monitor for my new 2020 MacBook Pro (running Catalina).

I am using a brand new 2020 MacBook Pro, USB-C to Thunderbolt adapter, Thunderbolt cable, plugged into the iMac's Thunderbolt port (not mini display).

I am quite unhappy that this appears to be apple purposefully rendering old products obsolete by not including backward compatibility software/code.

Will apple fix this in a software update? Should I return the new cable and adapter? Should I return the laptop too? I'm not sure I want to put up with this after spending nearly $4K on a new computer that doesn't work for my office needs.

Other users are also having this problem. It seems like target display mode is no longer supported on the new 2020 line of MacBooks, both air (https://forums.macrumors.com/threads/mba-2020-cant-connect-to-external-monitors.2229195/page-2) and Pro (https://apple.stackexchange.com/questions/392995/target-display-mode-not-working-on-macbook-pro-13-2020/393278?noredirect=1#comment541014_393278)

MacBook Pro 13″, macOS 10.15

Posted on Jun 10, 2020 7:42 AM

Best reply

Grant Bennet-Alder

Level 10

127,759 points

Posted on Jul 4, 2020 7:23 PM

All iMac models introduced in 2011, 2012, 2013, and mid 2014: Use a Thunderbolt cable to connect your iMac to a Thunderbolt or Thunderbolt 2 port on the other Mac. If the other Mac uses Thunderbolt 3, you can use the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter with your [genuine ThunderBolt] cable.

from:

Use your iMac as a display with target display mode - Apple Support

That's a genuine ThunderBolt cable, right, not just a Mini DisplayPort cable?

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Target Display Mode not working 2020 MacBook Pro (Catalina)

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