HW kbd Failed to set (null) as keyboard focus ios
Solution 1:
I've just encountered this exception running a Xamarin app on the simulator. It started occurring after I toggled the software keyboard off while debugging the app. Given the exception mentioning the keyboard I think that's what caused it.
Uninstalling the app from the emulator, cleaning and rebuilding fixed the issue for me.
Unsure if this bug is on Apple's side or Xamarin's.