2018 MacBook Pro Target Display Mode Not Working

• USB Type-C™ is a specific feature of a product, it is not a generic description. Think of “USB Type-C” as an adjective not as a noun. 

-- according to:

http://www.usb.org/developers/usbtypec/USB_Type-C_Language_Product_and_Packaging_Guidelines_FINAL.pdf

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This adapter is available for sale by Apple:

Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter - Apple

You would need a ThunderBolt-2 cable as well.

The cables required for different setups are described in this article as well:

Use your iMac as a display with Target Display Mode - Apple Support

.

and the list of "if it does not work" from the article are all does not apply?

If Command-F2 doesn't work

If your iMac doesn't switch to Target Display Mode when you press Command-F2, check these things:

• Make sure that the iMac you're trying to use as a display supports Target Display Mode. 
• Target Display Mode works only when your primary Mac is logged in to a macOS user account. For example, if your first Mac is at the FileVault login screen, pressing Command-F2 on your iMac does not enable Target Display Mode. You must first log in to your Mac (using a regular display, if necessary) before you can use an iMac in Target Display Mode.
• Make sure that you're pressing Command-F2 on the keyboard that's connected to the iMac you want to use as a display.
• In Keyboard System Preferences, if the checkbox is enabled for "Use all F1, F2, etc. keys as standard function keys," the key combination changes to Command-Fn-F2.
• Make sure that your Mini DisplayPort or Thunderbolt cable is connected to both computers.
• If you're currently logged in on the iMac you want to use as a display, try logging out to return to the login window. Then press Command-F2 again.
• Some older Apple keyboards and third-party keyboards might not allow Command-F2 to toggle display modes. If this happens, use the keyboard that came with your iMac to toggle Target Display Mode on and off. 
• If your iMac is currently started up in Windows, it won't enter Target Display Mode. Target Display Mode isn't supported in Boot Camp.

The connection described in the question is valid:
Use your iMac as a display with Target Display Mode - Apple Support

I have the same problem. I use my 2011 iMac (running on High Sierra OS) for target display to MacBook Pro (Retina, 15-inch, Mid 2014). The iMac was running very smooth as my target display. A few days ago, I just got 2018 MacBook Pro (running on High Sierra OS version 10.13.6 (17G2307)) and it's no longer able to connect to the 2011 iMac. After I read the discussion here, I chat with the Apple support. He told me to use Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter. I will get this cable tomorrow and will give you an update.

I also have this problem.

Brand new very pricey MBP 15" i7 with T3 connectors.

iMac Late-2009 27" with mini display port.

iMac still works fine as a 2nd screen with my old MBP 2012 13" via it's Thunderbolt (1?) port, running a mini display cable to the iMac's mini Display port.

In the new setup I am using the Apple T3-T2 adapter as per advised on this; Use your iMac as a display with Target Display Mode - Apple Support

And doing everything I can but it ain't showing up.

I'm currently chatting to a senior Apple support person after was fobbed off with 'go to Genius bar' earlier.

I will report if there's news.....

I just contacted apple and the result is nothing, blank. They couldn't even tell if the problem is going to be fixed and when. I told them to search in google "MacBook Pro 2018 target display mode". The first result is this discussion, just to show them that we are a lots of people that have the same frustrating problem. And remember MANY IS POWER, so each one of you that are following this chat and having this problem, please right a ticket to apple or even chat them or call them, and this bug will be solved earlier!!!
Writing a feedback: Product Feedback - Apple

I thought this but then Pennock pointed me into the direction of 10.14.1 the beta version of Mojave from here https://beta.apple.com/sp/betaprogram/

Since downloading and installing the target mode works like it did before on Sierra no problems 🙂

Unfortunately I have the same problem with my brand new 2018 13" MBP 😟

Configuration I'm using:

• Apple Thunderbolt Cable
• Apple Thunderbolt 2 to 3 (USB-C) Adapter
• 2013 iMac 27"
• 2018 MacBook Pro 13"

Is there an update coming soon? The beta of macOS Mojave 10.14 doesn't seems to fix the issue. Or do we have to wait for the official release!

My Story:

Late 2012 iMac (was running Sierra)

MacBook 2017 (not Pro)

Was so happy when I found out my iMac was capable of TDM.

Immediately forked out $90 for the two cables (tb3->tb2) and the (tb1->tb1), originals from Apple.

When I tried it according to the description i got a notification on my MacBook that thunderbolt devices are not supported.

Of course Apple for some reason chose not to support tb3 on the Macbooks from 2017, only a standard USB-C connector sans tb3 (not been watching the WWDC's since Steve passed and just expected tb3 to be on all new mac products).

Since then I purchased a new 13" MacBook Pro (2018) so that I would be able to hook up the old iMac (and will be selling my MacBook (2017)).

Getting this to work with the new MacBook Pro was a PITA, this is what I ended up doing:

• Installed latest version of Mojave (10.14.5) on both the iMac and the MacBook Pro (2018)
• Dug up the original iMac Bluetooth keyboard and connected it
• Logged Off the iMac
• Logged On the MacBook Pro (2018)
• On the iMac pressed Cmd & Fn & F2 (even though keyboard is set to use Function Keys!)

In retrospect I guess installing Mojave on the iMac was unnecessary.

If it doesn't work right away, keep pressing Cmd & F2 or Cmd, Fn & F2 at the log in screen on the iMac.

Good Luck!

I had a customer who has two Mac computers

• MacBook Pro (15-inch, 2018) - Mojave 10.14.6*

•iMac (27 inch, Late 2013) - Mojave 10.14.6*

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STEPS:

1. I kept the iMac on the login screen (if your iMac is logged in, please log them out.) By Pressing on the apple logo and clicking on the last option being "Log out ..."
2. on the MacBook Pro this time have them logged in (admin user) (which was the only user)
3. keep in mind the cable has to be connected to both Macs
4. and now to focus on the the iMac you basically press ----> CMD F2 > and it basically starts TDM

so now you see it as the iMac being the display as it isn't logged into a user and the MacBook Pro being the main Mac where it basically as would have the content viewable on the iMac

_____________________________________________________

I am not sure if it was supposed to be this way now whether it may be with Mojave or with other OS

but this certainly helped me. and I advise you try this as the very first step once you've done all other TS

Try sleep and wake the MacBook Pro and see if it finds the display attached.

If not look in

 main About this Mac > (System Report) > ???

??? maybe ThunderBolt? Graphics&Displays?

... to see if the iMac is detected as present in some form

I'm experiencing the same issues, exactly as you described them. I contacted Apple Support and a ticket was created, and eventually escalated. I recommend you also contact support so the issue can be tracked.

Another user has reached out to me, stated that they've spoken to support, and that support is aware of the issue here: Daniel Storm on Twitter: "Anyone else with the new 2018 MBP having issues with Target Display Mode?"