Bluetooth keyboard incorrect PIN or password - SOLVED
Just in case this helps anyone else, I had a nightmare today with my Bluetooth keyboard and my Android phone - but I used some common sense and found a geeky solution. In my case it was a ZTE Axon 7 running Lineage OS and a Microsoft Universal Folding Keyboard (UFK), but I suspect this cure will work for more general issues. The symptom was that when I tried to connect a previously paired keyboard I first of all got just the raw Bluetooth address shown and not the keyboard name. And then, when I tried connecting, I got an "incorrect PIN or password" error message. No chance to reenter a PIN and no amount of restarting keyboard or phone would fix it. The cure seemed to be to reset something in the phone's Bluetooth system, but what? The keyboard wasn't showing up as paired, so I couldn't 'forget' it. I tracked it down in the end. Settings, Apps, then 'Show system' on the '...' menu. Find and tap on 'Bluetooth extensions'....