Python code for Bluetooth throws error after I had to reset the adapter
I was trying out bluetooth programming in python. It was working fine till yesterday. This morning, there was a power outage and for some reason, the bluetooth module got disabled and it could not be turned on. So, I did a sudo hciconfig hci0 reset and then turned it on. From that point onwards, the simplest of the programs are failing to execute. Take this one for example. It gets stuck at advertise_service in bluetooth module and throws the following error (FYI: virtualenv was not a problem here. The systemwide python also does the same thing).
Traceback (most recent call last):
File "bt.py", line 17, in <module>
advertise_service( server_sock, "SampleServer", service_id = uuid, service_classes = [ uuid, SERIAL_PORT_CLASS ], profiles = [ SERIAL_PORT_PROFILE ])
File "/home/machinename/.virtualenvs/py27/local/lib/python2.7/site-packages/bluetooth/bluez.py", line 242, in advertise_service
raise BluetoothError (str (e))
bluetooth.btcommon.BluetoothError: (2, 'No such file or directory')
Sometimes I got a different error when I compiled and reinstalled Bluez driver:
Traceback (most recent call last):
File "build/bdist.linux-x86_64/egg/bluetooth/bluez.py", line 268, in advertise_service
bluetooth.btcommon.BluetoothError: error no advertisable device.
But all of these worked like a charm before in that machine; in fact all of the program works just fine with my other ubuntu (14.04LTS) machine as I write this. I inspected the source code, and traced to a _bluetooth.so file - which is a compiled code, hence I couldn't figure out what to do anymore.
Any pointer will be highly appreciated.
Answer
This error is due to incompatibility issues with BlueZ 5 and SDP with bluetoothd
Fix for 15.10 and BlueZ 5
Make sure, running sdptool browse local gives following error:
Failed to connect to SDP server on FF:FF:FF:00:00:00: No such file or directory
As it turns out, the culprit is bluetoothd, the Bluetooth daemon. Using SDP with bluetoothd requires deprecated features for some silly reason, so to fix this, the daemon must be started in compatibility mode with bluetoothd -C (or bluetooth --compat).
Find location of bluetooth.service by:
systemctl status bluetooth.service
Then edit bluetooth.service and look for
ExecStart=/usr/libexec/bluetooth/bluetoothd
Append --compat at the end of this line, save, and then run
service bluetooth start
If all goes well, you should be able to successfully run
sudo sdptool browse local
Finally, reset the adapter:
sudo hciconfig -a hci0 reset
Things should work fine now
Old answer
Just to let people know, I believe the latest BlueZ build was somehow broken in my system. I downloaded, compiled and installed the 5.35 version, and nothing was working. I dialed down to 5.34, still same. I also noticed that the bluetooth adapter was going down automatically 3-4 minutes after enabling it using,
sudo hciconfig hci0 up # hci0 is the bt adapter
I used one usb bluetooth dongle to test. It did not go down automatically like the inbuilt adapter, but the problems persisted. Then I used apt-get to reinstall bluez,
apt-get install --reinstall bluez
and all of a sudden everything came back to normal.