iMac High Sierra Upgrade - USB Keyboard not recognized

Worked for a while... updated point release last night... really?

After updating my own 27" late 13 model desktop, my USB apple keyboard no longer works either. I've tried resetting SMC, NVRAM, Disk Utility (first aid) and nothing works. The keyboard, when plugged into USB does show up when I look at System Information: USB. It just doesn't work at all. It started off by the space bar not working right after the "upgrade" to High Sierra then died altogether.

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 just updated my system before reading about it, and the same thing happened to me. I talked to them in chat and didn't resolve anything. Basically the only way to revert back is to erase your entire system.......who wants to do that?
I hooked up a windows keyboard and it works fine. I hooked up my wired keyboard to a windows computer and it works fine. But for some reason when the apple keyboard is hooked up to the apple laptop it doesn't work................ They told me my only other option was to go into the store, but being as it's the end of semester and I have the end of year rush of assignments that isn't going to be helpful. I wish they had an easier way to revert back to the previous OS. Or another way to back up the computer to the cloud..

What worked for me is.

Keep Apple keyboard plugged in then plugin another non-mac keyboard.

I tested with a couple of restarts. Apple keyboard does not work each time, then plugin the windows keyboard and the Apple keyboard starts working again.

#WindowsMakeAppleWork, well-done Apple

What has sometimes helped: switch off WIFI. try to connect Bluetooth device, then switch on WIFI.