I have a macbook pro (mid-2011) and an HP Pavilion 22bw (prob inconsequential) connected via a Thunderbolt DVI Adapter.

Ever since installing Yosemite, I now need to open the macbook pro and log in via its own screen, rather than the external monitor. It simply does not display / send any signal to the external screen until AFTER I'm logged in.

Does anyone else have this issue? Is there any other option? This is highly inconvenient with how my workspace is set up.


  • 1
    So how do you wake it up normally (without opening the lid)? Also what is the setting in your pmset -g- using terminal.
    – Ruskes
    Dec 17, 2014 at 17:20
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    for clam shell mode to work, the computer has to be plugged in to power outlet, but you know that! and you checked that your external keyboard and mouse are active. So the computer will wake with keyboard or mouse and activate the external display (that was in standbay mode).
    – Ruskes
    Dec 18, 2014 at 18:16
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    Is the external monitor set up as the main display? Feb 21, 2015 at 8:31
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    Incidentally, do you have FileVault enabled? I've only seen the login behaviour you describe on machines with FileVault enabled, other machines without FV seem to boot as expected... Mar 3, 2015 at 19:18
  • 1
    I have the exact same issue, and I have FileVault enabled... Aug 13, 2015 at 11:20

1 Answer 1


To Fix this issue do the following while your external monitor is plugged into the MacBook:

Open Displays in System Preferences Click on Arrangement at the top of the window If Mirror Displays is checked, uncheck it The position of the two displays should now be shown in the Displays Window One of them will have a white bar at the top. This is probably your MacBook Click on each display in the window and you will see the relevant display framed in red. If the white bar is at the top of your MacBook display, move it to the top of the external monitor display. Then click Mirror Displays again. This should resolve the issue

  • 1
    This doesn't work for me on Sierra. If I log out, the login screen will be displayed on both mirrored monitors, but after a reboot, only the built-in display will be active. I should note that I have FileVault enabled, which may presumably impact the loading of hardware drivers and/or display settings. I'll try to determine whether FileVault affects this issue and post back later.
    – oKtosiTe
    Jul 31, 2017 at 12:32

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