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El Capitan System Integrity Protection Update Breaks Ethernet

Many Mac users were baffled over the weekend when their Mac‘s Ethernet ports stopped working. Thankfully, Apple swiftly published a support article about how to fix the problem. The culprit appears to be an update to OS X 10.11 El Capitan’s System Integrity Protection security feature, which accidentally disabled the kernel extension that manages the Ethernet port.

Apple pushed out a second update to the Incompatible Kernel Extension Configuration Data that should automatically fix the problem. But if the first update disabled your Ethernet port and prevented the second update from installing, follow these steps to determine your situation and fix it:

  1. Hold down the Option key and choose System Information from the Apple menu.

  2. In System Information’s sidebar, under Software, select Installations.

  3. If the listings aren’t arranged in alphabetical order, click Software Name to sort them.

  4. Look for Incompatible Kernel Extension Configuration Data. If the most recent version installed is 3.28.1, you have the troublesome version, and will need to force an update to 3.28.2. If you already have 3.28.2, as in the screenshot below, the kernel extension isn’t the culprit and you’ll have to try another troubleshooting method.

If you need to force an update to 3.28.2 and have a Wi-Fi connection, the fix is easy: Open Terminal in /Applications/Utilities, type the following command, and press Return:

sudo softwareupdate --background

You may be prompted to enter your administrator password. After that, quit Terminal and restart your Mac to finish applying the fix.

If you can’t connect to Wi-Fi or don’t have a Wi-Fi network, then you unfortunately have a more involved process ahead of you, detailed in the aforementioned Apple support article.

We’re happy that Apple addressed this issue quickly, but we can’t say that the broken 3.28.1 update gives us warm and fuzzy feelings for the state of Apple’s software quality assurance.

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