Q: "System extension cannot be used" after installing iTunes 11.4

I am unable to Sync my iPad and iPhone5s now. This would be via USB - does anyone have this issue? I am on OS10.6.8  iTunes 11.4 and iOS 7.1.2. iTunes sees my devices, but won't sync or backup. I can restore an old backup to the device, but iTunes won't take anything from the devices. The sync button is greyed out, and when I try to do a Backup - Sync starts for maybe 1 second, and then stops with no error message. iTunes also does not see any new music (like the U2 album), and check for downloads says that nothing is available.

I can still sync my iPhone 4

But since you're running iOS 7.x…  you can sync wirelessly if you enable it…. I'd use WIFI to avoid  cellular charges (if it will even let you sync cellular)

Hi, I had the "//System/Library/Extensions/AppleUSBEthernetHost.kext " error too. Got it going by deleting the file and reinstalling a fresh one from a new copy of iTunes. However when I plug either iPhone 5 or iPad Air into iTunes on my iMac all the device contects are shown as 'other' and the sync button greyed out. Therefore I cannot even try to sync.

Any ideas what is wrong? Of course everything worked perfectly before the latest version of iTunes!

I did check that and nothing happened, I might have still been plugged in to USB. I will try again tonight.

This is exactly my situation too.

Hi, I have exactly the same problem as you. I am using the same older OS on my iMac and my iPhone 5 and iPad Air will not sync as the sync button is greyed out. Talked for hours yesterday with Apple support but they were no any help. Do not even recognise the problem and blame me using an older iMac.

If you find out anything can you please let me know. Thank you.

I should note… I'm syncing on Lion… 10.7.5  ….   (Mac Pro can't go to 10.8)…     Only Parallels 9 appears to have problem with kext under 10.7…     I haven't updated iTunes on my 10.8.5 machine.

I just updated to 11.4 and got the exact same message--but so far it doesn't appear to have affected anything. I can sync my iPod Touch using USB (I know it was connected via USB because when I unplugged the USB cable, the option to restore the iPod went away and instead the message to connect with cable to restore appeared). And I can print via USB, and backup to TimeMachine using USB as well.

I sent Apple feedback about it anyway--the message says to contact the vendor, does it not?

For the record, I'm running 10.6.8 (I have an old machine and every Apple Genius I've spoken to has told me NOT to update with this machine!).

Kept it simple and followed your approach nilsson58. Worked for me Thanks!

I also has this error msg.

I simply unplugged my dock, downloaded a fresh copy of iTunes, removed the offending file (in Terminal) using the instructions already provided:

sudo rm -Rf /System/Library/Extensions/AppleUSBEthernetHost.kext

…then installed the fresh copy of iTunes 11.4.

The dodgy file was replaced with a fresh copy (30/07/2014) as part of the install and everything is fine now.

MacOS 10.7.5

It seems that people are experiecing different causes behind this error, and have used varying solutions. since I started wt a clean mac, when I installed Mavericks, I'm guessing that Mac released several versions of either Mavericks or iTunes 11.4. I am not that skilled in the art of changing terminal information, so I sent a message to apple, that I'm sure thousands of others did. I get that error, but thankfully I am not having any problems using iTunes, my Mac, or syncing my iPhone. Still it ****** me off that Apple rushed the release of Mavericks, or iTunes 11.4 w/o proper testing. Yes it was free, but many didn't have a choice in the update. Some websites won't even use any other other apple OP systems, except for Mavericks anymore.

Thank you wldcrdace- I successfully followed your instructions.

same issue with installation of iTunes 11.4.

What are you supposed to do if your extensions folder is empty? I used spotlight to search for AppleUSBEthernetHost.kext and there were no results.

I'm tipping it's not a folder that Spotlight searches, as a Spotlight search doesn't find it on my computer either.

Go to <your hard drive>/System/Library/Extensions and it should be listed there.

Has anyone determined if Apple has updated the installer (software update or download) to address, and just didn't update the version number?     Any new build numbers in the installer currently available?