Q: can't pair bluetooth keyboard with Yosemite

Same issue for me, with a Logitech Bluetooth mouse.

I had to go out and buy a usb keyboard to login and fix the problem.

this worked for my apple wireless keyboard:

Open your Bluetooth preferences on your desktop, and remove your keyboard from the list of paired devices.

if your keyboard is paired to anything else, such as an ipad or iphone, unpair it from those devices as well.

now your keyboard will not be paired with anything.

put your keyboard in pairing mode by turning it off, then on. green light should blink to indicate in pairing mode.

open your bluetooth preferences, it should automatically find your keyboard and ask you to input the 8 digit code.

you are now paired again....

I had the same problem.  I tried resetting the PRAM; no help.  Eventually I went into bluetooth settings and removed both the keyboard and mouse, but they would not re-pair.  I had to pair the keyboard and mouse to another device (an android tablet), removed them from that device, then they repaired to the mac with no problems.  So far this seems to have worked, even after a reboot.

I'm having the same issue with my recently purchased keyboard. I have tried to pair it with my iPad, which it does, then remove it from there and retry on my Macbook Pro (2012) but it does not work. I have tried taking the batteries out, and waiting to install them until I have turned off and back on the computers bluetooth but nothing is working.  Suggestions are welcome!

Pairing to another device, seems to do the trick.  Thanks.

This worked for me

This worked like a charm for me, thanks.  Also add that you need to unpair keyboard from apple tv.

Yep - same problem. As suggested, I paired it with my iPhone, then removed it - it then came up on the MacBook Pro. Three minutes and sorted.

Same problem for me but this worked immediately without any need to pair/unpair with another device http://davemeehan.com/technology/how-to-reset-an-apple-wireless-bluetooth-keyboa rd-mouse-or-trackpad

I've had issues reconnecting my bluetooth keyboard & trackpad since upgrading to Yosimite.

I run this script via custom Automator Application:

1) Search for (Spotlight search) and run Automator

2) Click "New Document" at bottom

3) Choose "Application" for new file type

4) Click on "Utilities" from list

5) Double-Click "Run AppleScript"

6) Replace (* Your script goes here *) with:

do shell script "kextunload -b com.apple.iokit.BroadcomBluetoothHostControllerUSBTransport; kextload -b com.apple.iokit.BroadcomBluetoothHostControllerUSBTransport" with administrator privileges

7) Press play to test (will prompt for password)

8) File->Save to desktop or wherever

Run the automator app whenever bluetooth devices won't connect

Worked for me. Thanks!

Okay I must be doing something wrong. This is what I see and it doesn't work.

on run {input, parameters}

  (* do shell script  "kextunload -b com.apple.iokit.BroadcomBluetoothHostControllerUSBTransport; kextload -b com.apple.iokit.BroadcomBluetoothHostControllerUSBTransport" with administrator privileges*)

  return input

end run

Same problem here. Tried the pairing with another computer first and that worked. As soon as I removed the keyboard from that other computer, the keyboard appeared in the Bluetooth device list for the intended Yosemite computer.