Target Display mode not functioning latest beta

I have Mojave Beta 10.14.4 installed in two iMacs. The main iMac is a 2017 27" and the target display is a iMac 27" Late 2013. When I press the key combo cmd f2 The 2013 iMac turns black, but doesn't connect to the 2017 iMac. This was working on all prior betas. I have reset the PRAM and checked cables still no luck. Any ideas would be welcome.

You should report BETA issues to Apple, if it is a bug that wasn't present in previous BETAs or in the released version of the OS, they will need to address it for the next BETA.

Raz0rEdge said:

You should report BETA issues to Apple, if it is a bug that wasn't present in previous BETAs or in the released version of the OS, they will need to address it for the next BETA.

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I thought that was one of the first basic requirements of being a beta tester as laid out by the conditions from Apple.

Not much sense posting the problem to various Mac forums or even Facebook or twitter!!!


Apple Beta Software Program Agreement
https://beta.apple.com/sp/betaprogram/legal








- Patrick
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Raz0rEdge said:

You should report BETA issues to Apple, if it is a bug that wasn't present in previous BETAs or in the released version of the OS, they will need to address it for the next BETA.

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Yes I did report it, just thought someone found away around this.

Your best bet is to try the Apple communities where there might be more active beta testers who might have insights. There aren't that many people on these forums that install the beta software because, I for one, need my machine to be working a 100% all the time.

Raz0rEdge said:

Your best bet is to try the Apple communities where there might be more active beta testers who might have insights. There aren't that many people on these forums that install the beta software because, I for one, need my machine to be working a 100% all the time.

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Yes going to get to the Beta forum and try there.

@joel:

I don't know how you got it to work before, but Apple has specifically stated that target mode does not work with the 2017 Retina iMacs:

This from Apple:

Apple has definitively stated that new 2017 iMacs will not support Target Display Mode, a feature that previously allowed some iMac models between 2009 and 2014 to use their built-in display as an external monitor for another Mac connected via Mini Display Port or Thunderbolt.

Are you sure it was working before?

In support of our Admin chscag's comments, see here: https://support.apple.com/en-gb/HT204592

Look at the System Requirements. This is just one quote:

iMac (Retina 5K, 27-inch, Late 2014) and later iMac models can't be used as Target Display Mode displays.

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Ian

IWT said:

In support of our Admin chscag's comments, see here: https://support.apple.com/en-gb/HT204592

Look at the System Requirements. This is just one quote:

Ian

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Well the 2017 has always worked including beta 3, but the target display is the 2013 not the 2017 so it should work.

joelw135 said:

Well the 2017 has always worked including beta 3, but the target display is the 2013 not the 2017 so it should work.

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Now that you clarified that the 2013 model is the target and not the 2017, that sort of raises the question whether or not it's supposed to work both ways? My understanding of what Apple stated is that a retina 2017 iMac can not be used for target mode either way (receiver or giver) but I may be wrong about that since you state it did work at one time.

Maybe here to see if it's listed:
Use your iMac as a display with Target Display Mode
https://support.apple.com/en-us/HT204592

And note the added notation:

iMac (Retina 5K, 27-inch, Late 2014) and later iMac models can't be used as Target Display Mode displays.

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- Patrick
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Hey, Patrick, you're getting to be like me - having senior moments. I get these a lot, she tells me

Your post is close to a replica of mine in #8.

Ian

IWT said:

Hey, Patrick, you're getting to be like me - having senior moments. I get these a lot, she tells me

Your post is close to a replica of mine in #8.

Ian

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Son of a gun eh...??? Great minds think alike, they say. Wives opinions possibly may not be included.





- Patrick
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Well now that great minds agree... How about doing some of that detective work you're noted for Patrick and find out if a 2017 iMac can be targeted to a 2013 iMac. I'm not sure it can if I'm reading Apple correctly, but Joel insists that it was working before.

I'm not sure it can if I'm reading Apple correctly, but Joel insists that it was working before.

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I am sorry Charlie, but I have never really ever been able to interpret exactly what Apple says accurately, and even for those times I do, I find there is usually an exception.

Bottom-line, if something works it works I guess, but it may not work consistently or for other users. And if something was working but stops under different conditions, then likely something introduced with the new conditions was probably the cause. ie: change in OS version or modifications, but there would have to be more than one case to even imply the change was universal.

So endeth the possible case on causes.





- Patrick
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Well, here's some "research" which offers a Yes and No answer!

This article is in the NO category: https://appleinsider.com/articles/1...ort-target-display-mode-despite-thunderbolt-3

This Apple Community site claims NO to begin with, but then at least one member apparently got it working (if you read through the responses) ie YES: https://discussions.apple.com/thread/8042498

This is his/her quote:

FWIW: I just got the latest iMac (Late 2017). With adapter was able to connect it's Thunderbolt 3 to the Thunderbolt 2 on my older iMac (Late 2013) and (the real nice) Target Display mode works. Target Disk mode works.

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That's the best I can do

Ian

This article is in the NO category: https://appleinsider.com/articles/17...-thunderbolt-3

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Their comment leaves one to question what the actual emulation Options are, so anyone who wants it could check that out I guess.

There are other ways to emulate the hardware trick in order to stream the display of one computer's desktop on another machine, but Apple's hardware based approach offered a true monitor-quality use of the internal display.

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Good finds Ian.

So I guess the actual answer is: Yes, No or Maybe.

But NOT if you're using a macOS Mohave beta it seems, at least not without some change or hack.






- Patrick
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