BluetoothLeScanner start Scan only goes to Error code 2

Question

I turned on bluetooth on my phone and my phone is galaxy s8 with newest version. don't understand what I can't get bluetooth 4.0 device on call back.

Below is code snippet.

public class MainActivity extends AppCompatActivity {
private BluetoothLeScanner mBLEScanner;
BluetoothAdapter mBluetoothAdapter;
private static final long SCAN_PERIOD = 5000;

Handler mHandler=null;
Button btn;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    checkPermission();
    BluetoothAdapter bluetoothAdapter =  
    BluetoothAdapter.getDefaultAdapter();
    if(!bluetoothAdapter.isEnabled()){
        bluetoothAdapter.enable();

    }
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        mBLEScanner=bluetoothAdapter.getBluetoothLeScanner();
    }
    mHandler = new Handler();
    btn=(Button)findViewById(R.id.btn);
    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Log.e("main","now calling bluetooth low energy");
            scanLeDevice(true);
        }
    });
}

void checkPermission(){
    String[] permissions = {
            Manifest.permission.INTERNET,
            Manifest.permission.ACCESS_NETWORK_STATE,
            Manifest.permission.BLUETOOTH_ADMIN,
            Manifest.permission.BLUETOOTH,
            Manifest.permission.ACCESS_COARSE_LOCATION,
            Manifest.permission.ACCESS_FINE_LOCATION,

    };
    int permissionCheck = PackageManager.PERMISSION_GRANTED;
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        requestPermissions(new String[]. 
        {Manifest.permission.READ_PHONE_STATE}, 0);
        requestPermissions(new String[]
        {Manifest.permission.ACCESS_COARSE_LOCATION}, 1);
    }
    for (int i = 0; i < permissions.length; i++) {
        permissionCheck = ContextCompat.checkSelfPermission(this,      
        permissions[i]);

        if (permissionCheck == PackageManager.PERMISSION_DENIED) {
            Log.e("main", "denied" + permissions[i]);
            ActivityCompat.requestPermissions(this, permissions, i);
            if  
            (ActivityCompat.shouldShowRequestPermissionRationale(this, 
            permissions[i])) {
                Log.e("main", "shouldshow" + permissions[i]);

            } else {
                Log.e("main", "requesting" + permissions[i]);
                ActivityCompat.requestPermissions(this, permissions, i);

            }
            break;
        } else {
            Log.e("main", "granted" + permissions[i]);

        }

    }


}
@TargetApi(21)
private void scanLeDevice(final boolean enable) {
    if (enable) {
        //stops scanning after a pre-defined scan period

        mHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                if (Build.VERSION.SDK_INT < 21) {
                    System.out.println("BLE// mBluetoothAdapter.stopLeScan(mLeScanCallback) ");
                    mBluetoothAdapter.stopLeScan(mLeScanCallback);
                } else {
                    mBLEScanner.stopScan(mScanCallback);
                    System.out.println("BLE// mLEScanner.stopScan(mScanCallback) ");
                }
            }
        }, SCAN_PERIOD);

        if (Build.VERSION.SDK_INT < 21) {
            System.out.println("BLE// mBluetoothAdapter.startLeScan(mLeScanCallback)");
            mBluetoothAdapter.startLeScan(mLeScanCallback);
        } else {
            Log.e("main","starting scan for second"+mBLEScanner);

            mBLEScanner.startScan(mScanCallback);
        //mLEScanner.startScan(filters, settings, mScanCallback);
        }
    } else {
        if (Build.VERSION.SDK_INT < 21) {
            mBluetoothAdapter.stopLeScan(mLeScanCallback);
        } else {
            mBLEScanner.stopScan(mScanCallback);
        }
    }
}
private BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() {
    @Override
    public void onLeScan(final BluetoothDevice device, int rssi,
                         byte[] scanRecord) {

    }
};

private ScanCallback mScanCallback = new ScanCallback() {

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    @Override
    public void onScanResult(int callbackType, ScanResult result) {
        super.onScanResult(callbackType, result);


        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            Log.e("main","this name : "+result.getDevice().getName());
            Log.e("main","this addr : "+result.getDevice().getAddress());
        }
        BluetoothDevice btDevice = result.getDevice();
    }

    @Override
    public void onBatchScanResults(List<ScanResult> results) {
    }

    @Override
    public void onScanFailed(int errorCode) {
        Log.e("main", "Error Code: " + errorCode);
    }

};
}

and Log message is as below.

3:19:59.167 3251-3251/smartiot.ica.org.blelowtest E/main: grantedandroid.permission.INTERNET
06-13 23:19:59.167 3251-3251/smartiot.ica.org.blelowtest E/main: grantedandroid.permission.ACCESS_NETWORK_STATE
06-13 23:19:59.167 3251-3251/smartiot.ica.org.blelowtest E/main: grantedandroid.permission.BLUETOOTH_ADMIN
06-13 23:19:59.168 3251-3251/smartiot.ica.org.blelowtest E/main: grantedandroid.permission.BLUETOOTH
06-13 23:19:59.168 3251-3251/smartiot.ica.org.blelowtest E/main: deniedandroid.permission.ACCESS_COARSE_LOCATION
06-13 23:19:59.171 3251-3251/smartiot.ica.org.blelowtest E/main: requestingandroid.permission.ACCESS_COARSE_LOCATION
06-13 23:20:15.188 3251-3251/smartiot.ica.org.blelowtest E/main: now calling bluetooth low energy
06-13 23:20:15.189 3251-3251/smartiot.ica.org.blelowtest E/main: starting scan for secondandroid.bluetooth.le.BluetoothLeScanner@e24e0e4
06-13 23:20:15.264 3251-3251/smartiot.ica.org.blelowtest E/main: Error Code: 2

Manifest code is as below

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="smartiot.ica.org.mbluetooth">

<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.BLUETOOTH" />

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>
<uses-permission android:name="android.permission.READ_PHONE_STATE" />

<application

Answer 1

You should request the enabling of the bluetooth adapter at runtime with:

private void sendEnableBLERequestIntent() {
        Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
    }

Catch the startActivityForResult response here:

@Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_ENABLE_BT && resultCode == RESULT_OK) {
            // your stuff here
        }
    }

Answer 2

Have you declared thest in your manifest , find it from google from manifest and add that permisson i just copied from your code

run-time permission does not work without declaring in manifest file

Manifest.permission.INTERNET,
            Manifest.permission.ACCESS_NETWORK_STATE,
            Manifest.permission.BLUETOOTH_ADMIN,
            Manifest.permission.BLUETOOTH,
            Manifest.permission.ACCESS_COARSE_LOCATION,
            Manifest.permission.ACCESS_FINE_LOCATION,