"Ethernet Unplugged" ever since upgrading to Mavericks

It's possible that an SMC and/or a PRAM reset may help. Try the SMC first and test, followed by the PRAM if you're still having problems:

https://discussions.apple.com/docs/DOC-3603

Try the PRAM reset again - it can sometimes take a couple of PRAM resets to help resolve problems. When you hear the second chime, take your fingers off the keys and let the Mac boot up and test to see if the ethernet is working. It's not necessary at this point to do another restart - see, if it's fixed, and whether it continues to work. Of course, when you eventually shutdown/restart next time the test will beto see if the 'fix' sticks.

Another thing to try is a Safe Boot (you could try this if the PRAM reset doesn't permanently resolve the problem): restart holding down the Shift key until you see the grey progress bar, input your admin password when prompted, let the Mac complete booting and test the ethernet. Restart as normal from the Apple menu when done testing.

Have you tried shutting everything down, router, Mac - everything. Unplug everything, then replug and restart.

Bags1301 in this thread: https://discussions.apple.com/thread/5508432?answerId=23610573022#23610573022 was getting the same message. He connected a switch and somehow seemed to work for him. I'm just wondering if a total reboot-unplug-replug will refresh all the connections.

Forgive my ignorance, but where does the connection in the wall go to - a router, switch? How are you actually connected to the web? Presumably the connection in the wall goes to some device? If so, unplug/replug/reboot, etc. that.

I have the exact same issue, I will try the PRAM version, but no other magic formulaes of rebooting/unplugging/SMC'ing has worked so far. It still says "cable unplugged" in the Ethernet section in System Preferences.

Bummer.

stj.

I did some debugging yesterday.

Checked the Ethernet port itself, looks fine, visually. I rebooted back into Snow Leopard, no dice. I booted from an external disk running Mountain Lion, no change. So ,whatever it is, it must be pretty low level stuff.

stj.

I don't have a long term cure, but there is a temporary one that works for me. First of all I turn off my router, then I go to networks in system preferences. I ask it to assist me in setting up. I create a new location and indicate on the next screen that I want to use DSL, since every restart takes me back to WiFi. I then enter my password to allow changes in settings. I go back to the first assist screen and reset for Automatic, then I make sure that the highlighted indicators on the left are for DSL. I apply the changes and restart my routher/modem. And low and behold the router recognizes my ethernet connection. It continues to work for me, even when waking up from sleep, but all the above has to be done after a shutdown or restart. Apple tells me it is the logic board and bring it into an Apple Store. Sure is funny that all this started immediately after downloading Mavericks. I'm going to wait to take the Imac in until they figure out it is in the software.

I had same problem on an iMac since updating to mavericks we lost use of the Ethernet port. Purchased a thunderbolt to gigabit Ethernet from Apple and tried connected to Ethernet through that. Has worked great and soled the problem. Hope this helps

I also just upgraded to Mavericks and now my iMac 27inch (mid-2010) no longer recognizes my ethernet cord? Any advice anyone? Wifi works perfectly. Seems like this is becoming a common problem from my viewing of other forums. Any help is greatly appreciated.

We had exactly same problem on our iMac, bought a Thunderbolt ethernet connection and connected the ethernet via the Thunderbolt port - works great now.