hcitool lescan shows I/O error

Question

I\'m trying to do a lescan using hcitool on the raspberry pi.

The command prints out

Set scan parameters failed: Input/output error. 

Answer 1

Upgrading to bluez v5.43 fixed this for me.

To upgrade to the newest bluez, you need to do a "manual" installation (not apt-get), downloading from the bluez website. I recommend this video walkthrough if you are new installing packages or need help.

After installing the latest bluez, I had to run a couple commands before it worked.

1. systemctl daemon-reload : Restarts the system daemon.

2. sudo service bluetooth restart : Restarts the Bluetooth service.

3. sudo hciconfig hci0 up : This was needed for my Raspberry Pi 3, with the built-in BT found at hci0.

After these commands, sudo hcitool lescan and its variants all seem to work.