Recent OS X security update has disabled Ethernet port on some iMacs and MacBook Pros

By , Feb 27, 2016

iMac late-2015 family 001

In squashing software bugs, you inevitably introduce new ones—that’s a fact of life. According to a thread on Reddit, Apple’s recent OS X security update has inadvertently disabled the Ethernet port for some owners of Apple’s all-in-one desktop and the MacBook Pro notebook.

Making matter worse is the fact that Apple pushed this security update via the silent updating mechanism, according to a poster on Reddit who probably enabled the option in System Preferences → App Store that prompts OS X to automatically install system data files and security updates.

The security update in question is labeled “031-51913 Incompatible Kernel Extension Configuration Data 3.28.1” and it apparently blacklists the Broadcom BCM5701 driver.

Apple has since pulled the update from its servers.

People who have already installed the update and cannot use their Mac’s Ethernet port as a result, forcing them to use Wi-Fi to get online, should boot into OS X Recovery Mode and restore the following folder from a Time Machine backup or another Mac running the same OS X version:


RELATED: How to start up your Mac in Recovery Mode

“If this stays broken until Monday there are going to be a lot of pissed off Mac users come next week,” wrote the poster.

If your Mac is affected, the Ethernet Cards sub-section under the Hardware heading in the System Information window (Apple menu → About This Mac → System Report will read “This computer does not appear to have any PCI Ethernet cards installed.”

RELATED: How to reinstall OS X in Recovery Mode

Until Apple provides a fix, affected users can do a basic reinstallation of OS X using the El Capitan installer on a USB thumb drive or reinstall OS X in Recovery Mode.

RELATED: How to create USB install disk for OS X El Capitan

Reinstalling OS X won’t delete your personal files or settings.

“Generally you don’t need to erase your startup disk to reinstall OS X,” explains Apple. “The OS X Installer is designed to allow you to perform an install in place over the same version or earlier versions of OS X.”

We have reached out to Apple for commentary on the situation and will update this article if we receive their official response.

Source: Reddit

  • Share:
  • Follow:
  • chuckisbusy

    i have a late 2013 Macbook Air i7 and it affected me. Just rebooted and did a PRAM reset, and was good to go.

    • Fofer

      Your MacBook Air doesn’t have Ethernet.

      • chuckisbusy

        I use a thunderbolt ethernet adapter. Point I was making was I was having issues.

      • Fofer

        And my point was that you were not hit by thIs specific bug/issue. The symptom may have been similar, but the cause was not the same. If it was, no amount of rebooting or PRAM zapping would have fixed it.

  • andreasauwaerter

    PRAM reset didn’t work for my MBP 13” 2011.

  • antonioreyna

    my imac 5k is affected 🙁 i called tech support and they dont know about this issue, told me to reinstall OSX

    • KOLIBERk

      Apple seems to have released a fix.

      Go to About This Mac > System Report > Software > Installations. Sort by Install Date and check to see if you have Incompatible Kernel Extension Configuration Data version 3.28.2 installed. 3.28.1 is the version that caused problems.

      If you haven’t gotten 3.28.2 yet, try going into terminal and typing:

      sudo softwareupdate –background

      Enter your password when prompted. Should update in a bit. Keep checking System Report until you get it. Reboot and all should be well.

      • antonioreyna


        I got it fixed by manually remove the file then download the new package 😀

        Apple made me had a hard time with this bug >.<

  • Geoff

    Does this affect the Mac mini (Mid 2011)? My ethernet stopped working as of today and it shows no ethernet cards installed as listed above.

    • flashgordon

      I noticed on my imac that I showed no Ethernet cards installed also. My solution is shown above.

  • I have the same issue on my Mac Mini…..damn it!!!!!

  • Scotow

    5k iMac late 2015 here, got the problem.

  • Tara Salt

    I got screwed hard with this update. My ethernet stopped working, I could no longer use any apps or log in to update on the app store, and it even disabled my ability to AirPlay what was on my Mac to my AppleTV. The Apple support was great though – I am up and running again.

    • Jacob Sabat

      The Apple techs (2) i spoke with didn’t even know there was a problem with the update. What did you have to do to get the ethernet to work?

  • Jacob Sabat

    The Apple techs (2) i spoke with didn’t even know there was a problem with the update. What does one have to do to get the ethernet to work?

  • Anibal Schumacher

    any clue where to get that wallpaper??

    • Scotow

      Here it is, didn’t find better resolution.

      • Anibal Schumacher

        thanks man!

  • FarmerBob_I

    It killed my Main Monitor on my 2008 Mac Pro. My secondary one works. Back to 10.10.5 where both work. Apple has asked for further info.

  • Daniel Waske

    ok this explains a lot… I’ve been toying around with static IPs for my computers at home today when all of a sudden my Mac mini lost his LAN-connection to my router (“no ethernet cable connected”) so naturally I assumed I broke something in the process of changing network settings. Neither an SMC- nor a PRAM-reset solved the issue, nor did AHT find anything so as a last resort I just completely restored OSX by pressing Command+R before the Mac booted. And now, just after the restore was successfully completed I read this. Another 2 1/2 h wasted…

  • Tim9lives

    I’ve been screwing with my older iMac for hours. I just could not figure out why the ethernet disappeared all of the sudden. I and the Cox Cable Tech figured that my Ethernet card burned up. I was thinking I need a new computer.
    Thanks for the great article informing me that it was Apple’s Hidden Update.
    If I had done an update…and then lost Ethernet…..I would have been more inclined to think I had a software issue. Apple really screwed the pup this time.

  • flashgordon

    Concerning the late February 2016 imac security update turning off the Ethernet Port problem. It happened to me, I was upset. My Ethernet port is 170mb down, my wireless at this location is 30mb. Some things say to do the apple o.s. update after this happens. That didn’t help me. I think once this bad kext…. file gets on your machine you are in deep yogurt. I tried to use time machine to restore just the kext file he mentions above but it wouldn’t restore it. Time machine said it couldn’t restore a file that belongs to the o.s.. So then I did a time machine o.s. restore to feb 24 before this happens. That is pretty radical. It was doing some “first boot” thing when the machine came back up (acting like it was setting up icloud for the first time, loading all my mail from the beginning of time, etc) but it was basically ok. It fixed the Ethernet port problem so the solution of restoring a prior Yosemite release prior to 2/27/2016 is a pretty good solution. I had just installed Time Machine on a big backup drive. In this case I think it saved my bacon.

  • Gabrianne Domingos

    Formated my imac, reinstalled OSX El Capitan and still have the issue. Can’t connect via Ethernet. I’m going insane, 2 days trying to fix this.