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"System extension cannot be used" after installing iTunes 11.4

Installing latest version of iTunes (11.4) today led to the following error message:

System extension cannot be used

The system extension “//System/Library/Extensions/AppleUSBEthernetHost.kext” was installed improperly and cannot be used. Please try reinstalling it, or contact the product's vendor for an update.

I'm able to use my USB drive for Time Machine, and that appears to be functioning ok. Why this error message? Anyone else had it? And what does it mean for the continued safe operation of my MacBook? Would be reassuring to know if this is happening for anybody else, and if anyone else has found it affecting them. (Other than the distraction of getting a worrying error message that I take time out to report?)

Thanks in advance.

MacBook Pro, OS X Mavericks (10.9.4)

Posted on Sep 10, 2014 6:02 AM

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Posted on Sep 10, 2014 6:19 AM

I was having the same issue and had reinstalled iTunes a few times with no success. As an experiment, I redownloaded iTunes from Apple Site this morning and TURNED OFF my iPad. Turned it off not put it to sleep and reinstalled and all went well. I do not have an iPhone and the iPad is my only extra apple device. There was no message this time and so far so good. I have also not had any problems that I can see

38 replies

Sep 19, 2014 2:14 PM in response to Coola Boola

I think this problem has been fixed by Apple, I had to restore my system to before the iTunes 11.4 update was made available (unrelated issue) anyway when the update popped up in the app store again I let it sit there for a few days. Today I noticed it disappeared for several hours, then reappeared bundled together with an OS X update 10.9.5. My guess Apple fixed the AppleUsbethernethost.kext problem.

Jan 14, 2015 6:47 AM in response to Robleo59

Also, I unchecked updates so new versions of software wont upload,If it works why fix it, If you purchase new software make sure its compatible with your OS system. I had to reload my printer drivers as well. The new yosemite OS wont work on my 2007 macpro intel quad duo. I have 4 gig of memory and 1 tb hard drive. The only problem I ever had was a hard drive crashing and since I didnt have the os system disk I had to purchase the leopard os. But since I fixed the Appleusbethernethost.kext file. my 10 usb port hub works better, I mean now my android shows up and my card reader. Go figure


Mac Pro

"System extension cannot be used" after installing iTunes 11.4

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