Target Display Mode not working 2020 MacBook Pro (Catalina)

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I will have to sell my two iMacs like you and buy two monitors if I want to use my new 2020 MBP OR continue with my 2018 MBP and sell the 2020 MBP at a heavy loss but at least I will recover something instead of "looking at it and feel angry at Apple...."

Same issue here. Just wanted to add it also applies to the new 2020 iMac 5K. I can't use my old iMac mid-2012 as a target display anymore. Frustrating, and so much time wasted trying to figure this out!

Maybe I can add something here: the iMac 27 from 2009 has a mini Displayport and no thunderbolt on the back side and this one worked with my MBP 2020 with a non Apple USB-C to mini Displayport cable. Seems like with this model you can have any input device (also PCsor so) as it hasn't a thunderbolt connector yet. Maybe this helps somebody.

Cannot this be considered as a flagrant example of programmed obsolescence, just made intentionally for people to buy more display screens, to the detriment of the planet?

No. That only computes if consumer-grade displays were a core Apple business segment. As Apple now have only one display that starts at US$5000 😳, I would say they are not in the consumer display business.

And remember this process of depreaction started SIX years ago.

If a third-party prints incorrect information on some blog or FaceBook posts, who is really responsible? Can any company police the entire Web? No.

When I see stuff like that, I don't blindly head out to buy; I check Apple's specs and support documents first.

The right adapter of course! The display has its own thunderbolt 2 cable (that looks like the mini display port), that goes into an apple thunderbolt 2 female to the thunderbolt 3 (usb-C) one in the MBP.

maybe i can help, on youtube there was a guy, using a dock with its own thunderbolt controller and a bunch of dongles that do video over usb, to connect up to 5 or 6 displays to the new M1 macs, check it out: ***

perhaps one of those solutions/docks/cables/dongles can work for you?

also...

while my own mba M1 is still waiting to be shipped, i would like to know from others here, if it's true or not that any mac with a mini display port connector, such as 2009/2010 imacs can be successfully connected in TDM to an M1 mac using said solutions of the above video.

From reading all pages here, I suspect that will work, as the problem with newer combo's seems to be the thunderbolt limiting interoperability, while a mac with display port connecter, would most likely present as a vanilla display port monitor to any other device, when switched to TDM after it's booted and logged in.

I do hope so, because i got a 2010 imac which i want to use as a monitor on the m1 mac, nekt to a dvi equipped dell 24'' monitor from yesteryears.

[Link Edited by Moderator]

well, you are party right, display link does create a so called virtual graphics card in memory on cpu/gpu and uses compression to send out video over usb, then de-compresses it inside the used dongle, box or dock which is a display link certified-chipped product yes, which it will indeed decode that to the video signal a display needs, i.e. displayport, vga, hdmi, dvi etc.

But displaylink has come a long way in recent years, is widely supported on Mac, pc & linux, already sporting resolutions of up to 4k@60hz in multi monitor configurations and up to 5Kp60@30Hz in single monitor setups, depending on accessory type and make. Also dropped frames with the latest kits from the more common, top brands such as wavelink, plugable, startech & cable matters is mostly a thing of the past, due to in large part because of the enormous additional bandwidth that USB 3.1/3.2 and Thunderbolt 3 afford. (Completely ignoring the move to USB4 at this point, kicking off just about now, which is gonna make it better yet still to come...)

Also, as seen in the various youtube videos and multiple benchmarks, especially on the new M1 macs, it runs just as good as dedicated ie. native monitors would, due to the way the M1 handles encode-tasks with it’s high‑performance and high‑efficiency cores, while DisplayLink’s bandwidth adaptive codec is indeed proprietary to them and their partners, it’s also very similar to how the M1 does H.264 or H.265/HEVC encodes, which of course it does natively. 

So really, if you’re not doing anything crazy, like those hub/dock buyers you describe, who I asume moste likely cheaped out on the first dock they could find or are doing things like trying to add all the 4K HDR displays they can, you should be fine for most use cases nowadays anyway. If you limited the amount of moniters you use with display link of course.

See it like this, instead of watching to a native uncompressed video output, you're seeing your computer like you do Apple TV+: compressed video, which again, is fine for most people and use cases.

Both are Apple issued, the cable and adapter. It works fine from the 2017 MacBook Pro 13, just not the new 2020 model.

So the question is, is this a hardware deficiency in the new chipset from Intel, or is it software. If its the former there's not a lot we can do about it beyond being annoyed with Apple for not indicating this problem earlier.

[Edited by Moderator]

I'm fuming.

Apparently that prevented your seeing the previous response stating that you are talking to your fellow end-users here, not Apple.

In that post there is also a link, the ONLY web-based way to get your concerns before some one who gets and Apple paycheck.

Save your ire for them.

The information in the article you mention is partly incorrect/outdated (and the article is marked as "archived"): the iMac does not need an old macOS. In fact, I have an iMac from 2013 with Catalina and TDM is working perfectly (with a pre-2020 MBP, of course).

Disappointing to say the least! I'm having the exact same problem but with a MBP 2019 16" + iMac 27" late 2013. Very frustrating especially as it worked flawlessly with my MBP late 2015 15" and still continues to work. Imac and MBP 16 running latest version of Catalina, MBP 2015 running Sierra 10.12.6

There is absolutely no commercial interest for Apple to remove TDM and they can easily fix the issue with an update. I continue using my MBP 2018 flawlessly with my 2 iMacs and soon I may have to sell my few days old MBP 13” 2020 at a heavy discount instead of looking at it and get angrier and angrier!

ripshiner wrote:

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with a MBP 2019 16" + iMac 27" late 2013.

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According the article that is making every ELSE crazy, Your setup SHOULD work:

You can connect any of these older iMac models to another Mac from 2019 or earlier

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