According to the device tracker docs, known_devices.yaml should be auto-created (and that was the behavior I saw in earlier versions of hass) but apparently recent versions no longer do this and generate an error of “Unable to load /home/homeassistant/.homeassistant/known_devices.yaml: Config file not found: /home/homeassistant/.homeassistant/known_devices.yaml”.
Thanks. I just wonder how others are getting around it. The last version that I had running 0.86 something worked fine. When I changed my ip settings it all went to hell.
Cheers.