634      iPhone_iPad_Mac_apple

MacOS Sierra not recognizing external displays ...

Hi.

I've just upgraded to macOS Sierra on my MacBook Pro Retina Mid 2012.

After the upgrade, my Mac is not recognizing any external display:

I've tried HDMI and DisplayPort to VGA adapters.

The Retina monitor "blinks" but not signal is detected on external displays.

Also, after rebooting, also the retina monitor goes completely black (the mac has booted, because I can trigger Siri commands!).

To restore the situation I need to put the mac to sleep, plug in an hdmi monitor (which does nothing), wake up the mac and eject the plug. After this sequence the retina monitor goes back on (and only that!).

I've tried to reset NVRAM and SMC: no effect.

I've tried to boot into safe mode or recovery mode, but the retina monitor remains black, as well as any other external display (the same happens if I try too boot with or without a connected external display).

I'm stuck and have no idea on what to do. I cannot even try to reinstall the OS, as no video works just after reboot.

Any hint would be appreciated.

Thanks!

Hi agpastore,

Thank you for using Apple Support Communities. Based on what you stated, it seems like you are having trouble with the MacBook display and an external display both going black. It looks like you have already done some troubleshooting. I would recommend you read this article, it has some more steps that may be able to help troubleshoot the issue:

Get help with video issues on external displays connected to your Mac - Apple Support

Cheers.

Hi mario49,

thanks for your reply.

However none of the suggestions reported in the article were relevant or effective.

I had eventually to bring my MacBook at an Apple Store for assistance.

None of the technicians at the Genius Bar were immediately able to trace the problem,

which they never saw before.

The could not even boot the Mac over the network using their diagnostic tools...

(the retina display was totally black - not even the Apple logo on the back side)

Now I'm eagerly waiting for their response...

I have the same problem.

This is the message I get on the Console app when attaching an external display (Dell ST2420L) via a Thunderbolt to HDMI cable (it's for the WindowServer process):

[ERROR] - Driver reported mode info is out of sync with current mode info. Display 4280500, driver's bytePerRow = 10240, driver's width = 3360, stored width = 3360. Forcing rowbytes to be 4*modeInfo->ioModeInfo.nominalwitdh.

The message is repeated several times, and also appears when de-attaching the cable.

I have the same issue as well.  When attempting to connect with an external projector as a second monitor, the projector does not connect properly and all I see a blue/default screen.  Another issue I noticed is that when I start my computer with the projector connected to the iMac both screen go blank/purpleish black and all I see is a cursor that can be moved around.  However, when I unplug the thunderbolt adapter to the projector, the iMac screen comes back to the login screen.

There is definitely something wrong with macOS Sierra and I would really like to go back to the previous version.

I left my MacBook one week at a Genius Bar, they asked me about 500€ for replacing the whole motherboard, but I declined the offer, as I think (and hope nonetheless!) it's a software bug, not an hardware issue.

After getting the mac back, now it boots regularly, and when I connect an external display it seems to be recognized and working immediately, but within 15 secs it goes kernel panic'ing with a GPU panic fault and reboots.

My last attempt will be a downgrade to El Capitan...

I have the same console message as @oleguerilustrum, and I have recently updated to Sierra, but I have *never* attached this macbook to an external display. So I'm not sure what the reason for this message is, but it's nothing to do with external displays.

Same for me.

And external monitor is not working since upgrading to Sierra.

Is any of you experiencing also GPU kernel panics when connecting external monitors, or is this just happening to my macbook?

I have the same issue as well.  When attempting to connect a second monitor with a DisplayPort to VGA adapter, the monitor does not connect properly and I see is bluisht screen.  I've tried to reset NVRAM.

I don't see any kernel panics as far as I can see.
Did you try downgrading to El Capitan already?

I forgot to mention in my previous post that this issue happens ONLY when connecting with the Thunderbolt port to the external display with a Thunderbolt to HDMI cable adapter.

When I connect it with the Macbook Pro's HDMI port (with a regular HDMI to HDMI cable to the Dell external display) then it works. The only issue then is that several times a day, the external display goes black for some seconds (says Entering sleep mode) and then goes back to normal. This last issue already happened to me with El Capitan, and using an HDMI-to-DVI cable or using another different external display doesn't solve it (which makes me think there is an issue with the Mac's HDMI port).

My system is a MacBook Pro (Retina, 13-inch, Late 2012) with an Intel HD Graphics 4000 1536 MB graphics card.

Same problem

after upgrade external monitor does not work anymore

[ERROR] - Driver reported mode info is out of sync with current mode info. Display 42737c0, driver's bytePerRow = 6144, driver's width = 1680, stored width = 1680. Forcing rowbytes to be 4*modeInfo->ioModeInfo.nominalwitdh.

Control keys on bluetooth headphones does not work anymore too

Bluetooth Controls not working in Sierra

sierra is the biggest peace of **** I ever install to my mac's !

looking a way to downgrade this

Hadn't time to downgrade yet... Downgrading means resintalling everything from scratch as I have no El Capitan backups anymore...

They released an update today (October 25th 2016) that fixed this issue for me. Connecting my MacBook Air to an external display works again!

最後更新：2017-08-20 16:18:33

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