My MacBook Pro started to show this warning when coming back from sleeping to the login screen. It doesn't recognize its own keyboard and asks for an external keyboard. Once an external keyboard is plugged in, the internal keyboard works perfectly. 🤔
The screen says:
Bluetooth Setup Assistant
There isn't a keyboard connected.
Looking for a wireless keyboard. If one is found it will be paired with your computer. Check your cables if you expect to use a USB keyboard.
If you are attempting to use a wireless keyboard and it isn't found, make sure it is turned on and "discoverable." If you are using an Apple wireless keyboard, turn on your keyboard. If you are trying to use a non-Apple wireless keyboard, see the documentation that came with the keyboard.
No keyboards have been found. Make sure your keyboard is "discoverable."
macbook pro 13' retina - late 2013
macOS Sierra 10.12.6