IOException: read failed, socket might closed - Bluetooth on Android 4.3

Question

Currently I am trying to deal with a strange Exception when opening a BluetoothSocket on my Nexus 7 (2012), with Android 4.3 (Build JWR66Y, I guess the second 4.3 update). I

Answer 1

First, if you need to talk to a bluetooth 2.x device, this documentation states that :

Hint: If you are connecting to a Bluetooth serial board then try using the well-known SPP UUID 00001101-0000-1000-8000-00805F9B34FB. However if you are connecting to an Android peer then please generate your own unique UUID.

I didn't think that it would work, but only by replacing the UUID with 00001101-0000-1000-8000-00805F9B34FB it works. However, this code seems to handle the problem of SDK version, and you can just replace the function device.createRfcommSocketToServiceRecord(mMyUuid); with tmp = createBluetoothSocket(mmDevice); after defining the following method :

private BluetoothSocket createBluetoothSocket(BluetoothDevice device)
    throws IOException {
    if(Build.VERSION.SDK_INT >= 10){
        try {
            final Method m = device.getClass().getMethod("createInsecureRfcommSocketToServiceRecord", new Class[] { UUID.class });
            return (BluetoothSocket) m.invoke(device, mMyUuid);
        } catch (Exception e) {
            Log.e(TAG, "Could not create Insecure RFComm Connection",e);
        }
    }
    return  device.createRfcommSocketToServiceRecord(mMyUuid);
}

The source code isn't mine, but comes from this website.

Answer 2

On newer versions of Android, I was receiving this error because the adapter was still discovering when I attempted to connect to the socket. Even though I called the cancelDiscovery method on the Bluetooth adapter, I had to wait until the callback to the BroadcastReceiver's onReceive() method was called with the action BluetoothAdapter.ACTION_DISCOVERY_FINISHED.

Once I waited for the adapter to stop discovery, then the connect call on the socket succeeded.

Answer 3

I've had this problem and the solution was to use the special magic GUID.

            val id: UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB") // Any other GUID doesn't work.
            val device: BluetoothDevice = bta!!.bondedDevices.first { z -> z.name == deviceName }

            bts = device.createRfcommSocketToServiceRecord(id) // mPort is -1
            bts?.connect()
            // Start processing thread.

I suspect that these are the UUIDs that work:

var did: Array<ParcelUuid?> = device.uuids

However, I have not tried them all.

Answer 4

If another part of your code has already made a connection with the same socket and UUID, you get this error.