Thanks kiipro for the link, I suspect also tvheadend addon new version. I've forget on this installation to disable autoupdate ...
We should try to treat the cause. Does anyone know the reason?
Sorry I've not my K1 plus here but I remember tvheadend log show several ERRORs for some "duplicated entry" (channels ?) and try also to initialize (scan?) dvb-t. After reboot, no tvheadend process is running, a ps command show a [tvheadend] process (ghost process ?).
I will post later the logs tvheadend show.