Some Mac users who use wired network connections got an unwelcome surprise recently when Apple accidentally disabled their built-in Ethernet port. In some cases, that also led to Mac App Store connection issues, but there is a fix.
The problem is that Apple tagged the Ethernet kernel extension as invalid. If WiFi is turned on and your Mac has previously joined your wireless network, it's possible your Ethernet port is inactive and you don't even know.
Apple's accidental kernel extension issue disables your Mac's Ethernet port
You'll need to check your Ethernet kernel extension version to see it's time to do a little under the hood fix. Here's how:
- Option-click the Apple menu, then choose System Information
- Click Software in the left column to expand its view
- Select Installations
- Find Incompatible Kernel Extension Configuration Data in the list on the right
- What you don't want to see is version 3.28.1
If your Mac shows version 3.28.1, here's what to do:
- Launch Terminal. It's in Applications > Utilities
- Copy and paste this command into Terminal: sudo softwareupdate --background
You can fix the problem with a single Terminal command
- Press Return, then enter your administrator account password when prompted
- Restart your Mac
After a little Terminal trickery, your Mac's Ethernet port is up and running again
That's it. Your Ethernet port should be working just fine again. Apple fixed the problem for most people quick enough that they didn't even notice there was a problem—assuming they had WiFi Internet access. If your Mac's only available Internet connection is Ethernet, you can still fix the issue, but the steps are a bit more involved. You can check them out in the related knowledge base article.