USB tethering gone after upgrading to iOS 9 and iTunes 12.3 After upgrading my iPhone 6 to iOS 9, and iTunes to 12.3, I cannot use the Personal Hotspot via USB anymore. It worked fine until the updates.

Through WiFi it works fine, so the cause is not that Personal Hotspot wasn't turned on, or that the Cellular Data Network settings weren't correct. Also, after I plug in the USB, the device does show up in iTunes, and Image Capture sees it too.

So, Personal Hotspot works and USB works, but the two not together.

This is what the Network preferences show on OS X (Yosemite 10.10.5):
"Either the cable for iPhone USB is not plugged in or the device is not responding."



And here is a screenshot from the iPhone's Personal Hotspot. The blue badge shows I'm successfully connected via WiFi:



Also, it seems I'm not alone. Any pointers on how to fix it?
Update:
Per @SeeMeCode's answer, you can re-install iTunes to solve the problem.

Solved.
I found the solution here. It's caused by a damaged kernel extension /System/Library/Extensions/AppleUSBEthernetHost.kext.
When I check /var/log/system.log, sure enough there is:
Sep 17 08:00:58 wagner.local com.apple.kextd[45]: Kext id com.apple.driver.AppleUSBHostMergeProperties not found; removing personalities from kernel.
Sep 17 08:00:58 wagner.local com.apple.kextd[45]: ERROR: invalid signature for com.apple.macos.driver.AppleUSBEthernetHost, will not load

This extension is installed with iTunes, so the cause was update to iTunes 12.3, not iOS 9. I tried to download iTunes and reinstall it, but it just installed the same damaged version of the kernel extension. So instead, I replaced it from a Time Machine backup as both the currently installed and the backed up version had the same version number 7.0.
After a restart, USB tethering works again.
To distinguish between the two, here's what the working one looks like:

$ ls -lR /System/Library/Extensions/AppleUSBEthernetHost.kext
total 0
drwxr-xr-x  6 root  wheel  204 Jan 10  2015 Contents

/System/Library/Extensions/AppleUSBEthernetHost.kext/Contents:
total 16
-rw-r--r--  1 root  wheel  3202 Jan 10  2015 Info.plist
drwxr-xr-x  3 root  wheel   102 Jan 10  2015 MacOS
drwxr-xr-x  3 root  wheel   102 Jan 10  2015 _CodeSignature
-rw-r--r--  1 root  wheel   474 Jan 10  2015 version.plist

/System/Library/Extensions/AppleUSBEthernetHost.kext/Contents/MacOS:
total 128
-rwxr-xr-x  1 root  wheel  63024 Jan 10  2015 AppleUSBEthernetHost

/System/Library/Extensions/AppleUSBEthernetHost.kext/Contents/_CodeSignature:
total 8
-rw-r--r--  1 root  wheel  3668 Jan 10  2015 CodeResources

And the damaged one:

$ ls -lR AppleUSBEthernetHost.kext
total 0
drwxr-xr-x  5 ischeini  staff  170 Aug  5 00:30 Contents

Contents:
total 16
-rw-r--r--@ 1 ischeini  staff  3202 Aug  5 00:30 Info.plist
drwxr-xr-x  3 ischeini  staff   102 Aug  5 00:30 MacOS
-rw-r--r--@ 1 ischeini  staff   473 Aug  5 00:30 version.plist

Contents/MacOS:
total 144
-rwxr-xr-x@ 1 ischeini  staff  71792 Aug  5 00:30 AppleUSBEthernetHost