bluetooth lowenergy - hcitool lescan returning error -

i'm running bluez 5.41 on rpi 3 , i'm getting error. up/down/reset don't nor power cycle.

    pi@rpitester:~/ble-stuff $ hciconfig hci0:   type: primary  bus: uart         bd address: b8:27:eb:f0:83:f1  acl mtu: 1021:8  sco mtu: 64:1         running pscan         rx bytes:8883 acl:40 sco:0 events:634 errors:0         tx bytes:7685 acl:43 sco:0 commands:488 errors:0  pi@rpitester:~/ble-stuff $ sudo /home/pi/bluez/bluez-5.41/tools/hcitool lescan set scan parameters failed: input/output error pi@rpitester:~/ble-stuff $ 

where start try , debug this? 1 odd thing noticed hci0 device on uart bus , not dbus. normal rpi bt?

as workaround, executing following command made hcitool work again:

bluetoothctl 

after restarting machine error appears again.

there notes raspberry pi 3 , uart: https://raspberrypi.stackexchange.com/a/45571