iMac High Sierra Upgrade - USB Keyboard not recognized

So, I had the same problem and the following worked for me. (I have no idea why)

1. Unplug the USB keyboard.

2. Reboot with the keyboard unattached.

3. When the machine is all the way back up, plug the USB keyboard in. It recognized the USB keyboard then.

Hope this works for you, too.

Thank you. That worked. I shut down the iMac, then unplugged it, then disconnected the USB keyboard. Then I powered it on without the keyboard attached. Once it was completely booted up, I plugged in the USB keyboard and it worked.

Strange, the thread I was responding to disappeared. I tried the plugging my Apple USB keyboard into a windows computer, where it worked just fine, and then I plugged my Apple USB keyboard back into my iMac27 (2013) again. That worked and it only took 1 minute to fix the problem!

I reset PRAM, SMC, unplugged replugged keyboard repeatedly. Nothing. Keyboard worked right before upgrade, now it does not. Luckily I had a wireless keyboard I could use hand, otherwise this would be even worse. How do I get this fixed???

Tried resetting with P+R and tried the other altAhift option and 15 min unplug. No go. Tried USB hub, no go. Tried different wired keyboard, no go. Wireless works and both wired keyboards (Apple) work (when tried on other computers). USB slots work for mouse for other devices. Power is going to keyboard as I can attach mouse to keyboard hub and it works but it’s like a driver or something is missing to recognize anything. Noticed the number 4 and brightness keys are sent sporadically to the Mac.

This doesn’t happen when attached to any other pc or mac only this iMac.

IMAC 27’ 2011. Barely used as it’s a family computer.

So what to do!?

Just updated to High Sierra and I've got a similar problem. Apple wired keyboard (A1243) was plugged into USB port on back of my 24" cinema display and now isn't working there. Other peripherals seem to work through the monitor but not the keyboard. Only solution is to hook up the keyboard directly to my Mac mini, which requires me to unplug something else and screws up my whole setup. Why shouldn't the keyboard work through the monitor like any other peripheral?

I too have this issue. On both my USB keyboard, which is non functional, and my Bluetooth keyboard which has some keys that don’t work and some that do, and some that pressed just repeat ad infinitum.

I have reinstalled. Rebooted. Unplugged for hours. New batteries. Reset NVRAM with terminal. Every suggestion here. And no luck. I was in the middle of selling my iMac (2011) to buy a brand new iMac. I’ve had to turn down two buyers because I can’t freaking log in!

Apple, you need to fix this ASAP.

I'm also having this issue - randomly - after installing the latest update from Apple (10.13.2 update)... This is also the only update I've ever installed that completely froze at about 75%. Read online that power-cycling would allow me to re-attempt the update, and it did. But now the random keyboard issues. The USB trackball connected through the USB port on the keyboard continues to work ironically. I have a Late 2014 iMac Retina 5k.

Strange as it may seem, if I disconnect the Apple usb keyboard and plug it into a windows based computer, and that computer recognizes the keyboard (always does, btw), then I disconnect that keyboard from windows and plug that same keyboard back into my iMac27, it works again. I have had to do this 3 times in the past month with each successive “update” to the iOS. Irritating, but very predictable.

I am having this issue Late 2013 27" iMac. I'm using a USB keyboard (WASD mechanical). It worked just fine on this computer with Sierra and El Cap before. However, I just upgraded today to high sierra (10.13.2) and after it goes to sleep and wakes up the keyboard won't work until I unplug it, wait several seconds, and then plug it back in (to type in the password). I just tried it out after sleeping and waking on a PC and it was just fine.

Clearly there's an issue with the USB bus after waking. Just a little annoying having to reach back each time it wakes up to do this :-/

Thank you! I had the same problem with my old Macbook Air from 2013 or 2014 when I updated it to High Sierra, and I unplugged my Apple USB keyboard and plugged back in and got that to work.

My new 2017 Macbook Air with High Sierra, though, was not recognizing the same keyboard after unplugging and plugging back in multiple times and trying to repair the disk permissions. So, I tried this and it worked! I kept the computer on and worked without the keyboard for 3 hours, then I plugged it in. At first it didn't seem to work and I unplugged it, then I plugged it back in and waited a minute or so and it is now WORKING! Thank you!

I managed to fix the USB keyboard problem, by using the USB Extension cord between the keyboard USB Cable and the computer USB port. Then, for some reason the keyboard always shows up after the computer goes to sleep.

After upgrading my Mac (3.06 GHz processor, Late 2009) to OS High Sierra Version 10.13.2. At first the unit didn’t recognize my keyboard. I unplugged the USB and reinstalled it and it began working again. However all the keyboard shortcuts no longer work. I also noticed my OS X mail not working and wouldn’t accept my password. After puttering around without any changes, my outgoing mail started working but not the incoming mail still hangs without receiving mail. I also have items now in my startup that were not there before.

I am so used to using my keyboard shortcuts, I’ll try to cut, paste, copy and undo but now my documents receive, ≈, √, ç and Ω. Very irritating because I am constantly back and forth between Mac’s.

Can't wait to see what else is not functioning correctly....Yippy-ki-A

Hey Scott - many thanks for that. As others have said, resetting SMC and VRAM was a complete waste of time for me too. However, I picked up on your suggestion of connecting the "dead" (from High Sierra's point of view) keyboard to a Windows machine. I tried this and it worked perfectly. Thanks *VERY* much for that. When I first plugged the keyboard in, Windows seemed to recognise that the keyboard was screwed, and I got garbage as I typed. But the more I typed, the better things got until it was fixed. Then I unplugged, reconnected to the Mac and - perfect! So, Windows PC's do have their uses after all! But seriously Apple - what are you guys playing at?

I have got similar issue with my MacBook Air (2013). Using an extension wire USB or a hub works for me. Maybe I have troubles with physical connection, I do not know, however my keyboard works on other device directly.