Strange bug: MBP hangs on boot when external monitor attached

Discussion in 'OS X Mountain Lion (10.8)' started by marekkurlmann, Aug 22, 2012.

  1. marekkurlmann, Aug 22, 2012
    Last edited: Aug 22, 2012

    marekkurlmann macrumors regular

    Mar 6, 2007
    I'm experiencing a strange bug: My mid-2012 13" MBP hangs when booting whenever my monitor is attached via the Thunderbolt port. Disconnecting the monitor solves the problem every time.

    I'm able to get as far as displaying the Apple logo on the MBP's screen; the external monitor displays a light blue screen. It's impossible to get past this point. Connecting the monitor after booting to Mountain Lion is no problem at all.

    FYI, I am using a Dell 2408WFP monitor connected via DVI connected to the MBP using the Apple DVI-to-Display Port adapter.
  2. Krazy Bill macrumors 68030

    Krazy Bill

    Dec 21, 2011
    Not exactly "Apples to Apples" but I'm on SL with an early 2011 MBP13. No problems here using the same monitor.
  3. arkmannj macrumors 68000


    Oct 1, 2003
    I often get hung up on a bluish colored screen when booting up if I have two screens attached.

    Mac Mini Server 2011 (Purchased with Lion, Upgraded to Mountain Lion)
    2Ghz i7, 8GB RAM (512MB dedicated to VRAM), Intel HD Graphics 3000

    Display 1) Thunderbolt to DVI adapter hooked up to a ViewSonic VX2245wm (1680 x 1050)
    Display 2) HDMI to HDMI hooked up to a Samsung S27A350H / SMS27A350H (1920x1080)
    When booting does work it tries to use Display 1 as the primary, but then at the login switches to Display 2 (My Preference for main)

    So often at boot I will disconnect the HDMI cable from the Mac Mini and then boot seems fine. (reconnect cable after login)

    as a side note I wish Apple would have left the Display menu in the menu bar so you could quickly say detect displays switch mirroring/extended/etc... it was much more convenient.
  4. gutenmac macrumors newbie

    Oct 15, 2012
    ML won't boot with external monitor

    Yes indeed, I picked up my new MBP Retina only to find it won't boot when an external monitor is plugged in... I have had no problem with my older 2009 MBP on SL... but once I upgraded it to ML, same problem - no boot with external monitor attached.

    I could go on about ML flushing the keyboard buffer several times when coming up from sleep as well. Honestly, I am really disappointed that my startup time is actually slower on ML than SL due to these issues, even with "all-flash storage". It reminds me of those horrid MSFT days watching the computer shoot, shoot, shoot, shoot until it finds a target that works... arrrgh!
  5. jk73 macrumors 6502

    Jul 19, 2012
    Could you tell me what the above means? I have an rMBP and I love it, but it seems to have problems waking from sleep (or from a locked screen) occasionally. (The keyboard backlight comes on, but the screen stays black, and I have to force a shutdown and restart.)

    This problem and an occasional problem with very slow shutdowns are the biggest issues I'm having. As much as I love the machine, my confidence in it isn't the highest right now. I hope this is a 10.8.x problem and not a hardware problem. Thanks.
  6. musanim macrumors newbie

    May 14, 2009
    I'm having a similar problem under El Capitan. The differences: nothing appears on the screen, and the boot sequence does not resume if I disconnect the external display (I need to disconnect it and restart the boot sequence).
  7. kryo macrumors newbie

    Jun 18, 2016
    I'm having the same issue with my Imac 21.5 inch late 2015 model. Was there ever a fix or work around identified for this issue?
  8. hanzzzen macrumors newbie

    Jul 30, 2009
    Odense, Denmark
    Quite funny... or not really. Same bug here – with my Macbook Pro. If monitors (I have two – a Dell and an Asus) are attached MacBook will not boot. If monitors are not attached during start – but after – external monitors work fine. Doesn't matter if I only have one of them attached – won't boot if connected during start. Black screen.

    Another issue – might be related – one of the usb ports will not generate enough power when connected to my iPhone. USB on the other side will... so... this might be related to the power supply somehow.
  9. HiRez macrumors 603


    Jan 6, 2004
    Western US
    Me too, this is still happening (2014 Retina MBP, El Cap 10.11.6) with regard to extremely slow boot times. No HDMI monitor attached: boot in ~20 seconds. With monitor attached: like almost 5 minutes. It's insane.

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8 August 22, 2012