I built a Java app where I implemented bluetooth functionality. Using the documentation I managed to discover devices and pair with them. I managed to get the whole device info (address, name), but it fails when I want to establish communication with the module.

In the ConnectThread constructor:

if (ContextCompat.checkSelfPermission(context, Manifest.permission.BLUETOOTH_CONNECT) == PackageManager.PERMISSION_GRANTED) {
            try {
                tmp = device.createRfcommSocketToServiceRecord(UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"));
            } catch (IOException e) {
                Log.e(TAG, "Socket's create() method failed", e);
            }
        } else {
            Log.e(TAG, "Missing BLUETOOTH_CONNECT permission");
        }
        targetSocket = tmp;

In the ConnectThread method run():

bluetoothAdapter.cancelDiscovery();

try {
    targetSocket.connect();
    Log.i(TAG, "Connection successful!");
} catch (IOException e) {
    Log.d(TAG, Log.getStackTraceString(e));
    Log.e(TAG, "Could not connect; closing socket", e);
    try {
        targetSocket.close();
    } catch (IOException e2) {
        Log.e(TAG, "Could not close the client socket", e2);
    }
}

In the MainActivity, when I choose a device from the paired devices list:

ConnectThread connectThread = new ConnectThread(device, mBluetoothManager, MainActivity.this);
connectThread.start();

**
What I have in my LOGCAT**

ConnectThread           com.example.carcontroller            D  java.io.IOException: read failed, socket might closed or timeout, read ret: -1
                                                                                                        at android.bluetooth.BluetoothSocket.readAll(BluetoothSocket.java:1170)
                                                                                                        at android.bluetooth.BluetoothSocket.readInt(BluetoothSocket.java:1188)
                                                                                                        at android.bluetooth.BluetoothSocket.connect(BluetoothSocket.java:566)
                                                                                                        at com.example.carcontroller.ConnectThread.run(ConnectThread.java:50)
ConnectThread           com.example.carcontroller            E  Could not connect; closing socket
                                                                                                    java.io.IOException: read failed, socket might closed or timeout, read ret: -1
                                                                                                        at android.bluetooth.BluetoothSocket.readAll(BluetoothSocket.java:1170)
                                                                                                        at android.bluetooth.BluetoothSocket.readInt(BluetoothSocket.java:1188)
                                                                                                        at android.bluetooth.BluetoothSocket.connect(BluetoothSocket.java:566)
                                                                                                        at com.example.carcontroller.ConnectThread.run(ConnectThread.java:50)

Using the Serial Bluetooth Terminal from google play I managed to connect to my module and send data so I figure that the problem is on my end but I can't find any information about why this happens.