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Command F2 not working after upgrade to Sierra

I have been using my 27" iMac as the target display for my headless Mac Mini for years ... with the latest being El Capitan.  After upgrading to Sierra, I can no longer use Command F2 to switch to target display mode.  Pressing Command F2 now just shows a black blank screen.  I can toggle it back to iMac display ... so seems that the Command F2 toggle is working but just that the display doesn't show up.

 

Anyone with this same issue?

The latest recent upgraded 10.12.2 has resolved this issue for me.

Hi prapi01,

 

Welcome to the Apple Support Communities!

 

We understand from your post that you have used Target Display Mode before in the past, but after upgrading to macOS Sierra, it is no longer functioning with the Command-F2 command as you would expect. 

 

To troubleshoot this situation, we recommend that you read over the information in the following article, especially the “If Command-F2 doesn’t work” section. 

 

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

 

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 the iMac you're trying to use as a display supports Target Display Mode. 
  • Make sure 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 functions keys, the key combination changes to Command-Fn-F2.
  • Make sure 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.

 

Cheers!

Allen, thank you for your reply. 

 

I have checked all that the article suggested and I have also reset PRAM and SMC just for good measure.  However, the problem persisted.  The ONLY difference is the Sierra upgrade since I was using Command F2 on a daily basis under El Capitan.

Hello prapi01,

 

Thanks for the follow-up and letting us know more about the situation and the steps you have tried. At this point, because the previous steps we suggested and the resets you performed have not resolved the situation, we suggest contacting Apple Support directly. 

 

Official Apple Support

 

Have a great day!

I can confirm this is happening in the new Sierra OS. In order to move forward, I wanted to clear up the troubleshooting suggestions (in bold):

 

If Command-F2 doesn't work

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

 

Of course it supports it, I, and the user reporting the bug, have used it successfully in the past

 

  • Make sure you're pressing Command-F2 on the keyboard that's connected to the iMac you want to use as a display.

 

I can confirm I am pressing Command-F2 on the display I want to use, and getting a blank black screen

 

  • In Keyboard System Preferences, if the checkbox is enabled for Use all F1, F2, etc. keys as standard functions keys, the key combination changes to Command-Fn-F2.

 

I can confirm I am using the F keys as function keys and not standard. To further illustrate that point, when I hit Command-F2, the display attempts to go into TDM, but just returns a black screen.

 

  • Make sure your Mini DisplayPort or Thunderbolt cable is connected to both computers.


I can confirm both cables are thoroughly, securely, and unequivocally attached to both machines.

 

  • 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.


I have logged out, logged in, and reset both machines. Problem still exists.

 

  • 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.

 

I am using an Apple keyboard that is less than a year old.

 

  • 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.

 

I am not starting the mac in Windows. I am booting in Mac OS Sierra on both machines.

 

Now that we have the copy/paste from the troubleshooting guide out of the way. Is there an actual solution to this apparent bug in Sierra?

I have the exact same issue.  I use my mac mini via my iMac daily and this feature was working correctly immediately before upgrading to Sierra.  I also have a black screen when switching over via <cmd> F2.  I, too, have reset my SMC and NVRAM/PRAM to no effect.  Note that I can access my mac mini through the "Share Screen..." feature in Finder, so I know that it is working.  This is a bug.

 

iMac (27-inch, Late 2012)

Processor  3.4 GHz Intel Core i7

Memory  32 GB 1600 MHz DDR3

Graphics  NVIDIA GeForce GTX 680MX 2048 MB

 

Mac mini (Late 2014)

Processor  2.6 GHz Intel Core i5

Memory  16GB 1600 MHz DDR3

Graphics  Intel Iris

VRAM (Dynamic, Max):  1536 MB

Vendor:  Intel (-x8086)

Device ID:  0x0a2e

Revision ID:  0x0009

Metal:  Supported

 

macOS 10.12.1 on both systems.

It's possible it's a bug. You can file a bug report here…

https://www.apple.com/feedback/macosx.html

I have just filed a bug report.

Any update on this issue? Having the same trouble here with my Mac Pro

 

Both updated to the latest version of the OS

No update yet, but I am hoping for an fix in the next Sierra update (I am currently on 10.12.1).  In the meantime, I encourage you to file a bug report to help Apple diagnose the issue and to confirm that multiple users are having issues (bug report link above) Provide your system details, e.g.

Hardware Overview:

 

  Model Name: iMac

  Model Identifier: iMac13,2

  Processor Name: Intel Core i7

  Processor Speed: 3.4 GHz

  Number of Processors: 1

  Total Number of Cores: 4

  L2 Cache (per Core): 256 KB

  L3 Cache: 8 MB

  Memory: 32 GB

  Boot ROM Version: IM131.010A.B09

  SMC Version (system): 2.11f14

 

NVIDIA GeForce GTX 680MX:

 

  Chipset Model: NVIDIA GeForce GTX 680MX

  Type: GPU

  Bus: PCIe

  PCIe Lane Width: x16

  VRAM (Total): 2048 MB

  Vendor: NVIDIA (0x10de)

  Device ID: 0x11a3

  Revision ID: 0x00a2

  ROM Revision: 3707

  Metal: Supported

  Displays:

iMac:

  Display Type: LCD

  Resolution: 2560 x 1440

  Pixel Depth: 32-Bit Color (ARGB8888)

  Main Display: Yes

  Mirror: Off

  Online: Yes

  Automatically Adjust Brightness: Yes

  Built-In: Yes

Found the solution. Still a bug and will need to be updated soon so please report to apple.

 

Restart both machines and on the chime, hold Cmd+ALT+P+R on the restart of each machine. This resets your P Ramm.

AsterL ... it's tough to do Cmd+ALT+P+R on a headless, keyboardless MacMini ... I did that on the iMac side but, of course, didn't solved the problem

Only now coming across this thread, I would like to add my $0.02:

 

1) It is clear that the iMac is responding to Command-F2, so the issue seems to be the Mac Mini's outputting some display resolution that is wrong for the iMac.

2) This is particularly difficult because of the headless nature of the Mini. If a user can do screen sharing to the affected mini, it would be interesting to see what one gets from System Preferences->Displays in this case - in particular, to confirm that the Mini detects the display is attached, and which resolution it is outputting to it.

 

FWIW, I use target display mode just about everyday, albeit in a different situation - to add a second display to my rMBP - and it works flawlessly. Again, the headless nature of the Mini seems to be the crux of the matter.

exact same issue since sierra.. I now have a very expensive desk ornament777.jpg.

All the others affected so far appear to be using *headless* minis.

Your experience seems unique in that you are unable to use target display mode from an imac to another.

You should be able to try the proposed solution (reset NVRAM on both computers, but more specifically the one that is the source, as the other one appears to correctly enter TDM).

最后更新：2017-08-22 10:20:46

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