My Android app scans BLE devices, and from a certain point it start to fails with error code 2 (ScanCallback.SCAN_FAILED_APPLICATION_REGISTRATION_FAILED). I'm using Nexus 9, 5.0.1 Lollipop.
This problem continued even after I relaunched the app, and when I restarted the Bluetooth service from Settings, I could finally get rid of the problem. But this problem is recurring, and I think I'm coding in a wrong way; BLE related APIs are new and there is few information.
Does anyone know a general solution for this error, preferably not requiring restart of the Bluetooth service? Even though this error code is documented in Android API reference, I don't know how to handle it properly.
When you got the error
SCAN_FAILED_APPLICATION_REGISTRATION_FAILED
You should disable the BluetoothAdapter
BluetoothAdapter.getDefaultAdapter().disable();
Disabling BluetoothAdapter, the event STATE_TURNING_OFF is fired. Once this event is fired, try to reconnect to the BluetoothAdapter:
case BluetoothAdapter.STATE_OFF:
Log.d(TAG, "bluetooth adapter turned off");
handler.postDelayed(new Runnable() {
@Override
public void run() {
Log.d(TAG, "bluetooth adapter try to enable");
BluetoothAdapter.getDefaultAdapter().enable();
}}, 500);
break;
It turns out that Bluetooth LE requires the following Android application permissions in AndroidManifest.xml:
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<!--BLE scanning is commonly used to determine a user's location with Bluetooth LE beacons. -->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<!-- if your app targets API level 21 or higher. -->
<uses-feature android:name="android.hardware.location.gps" />
<!--app is available to BLE-capable devices only. -->
<uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>
Besides on main activity:
// onResume()
if (ContextCompat.checkSelfPermission(this.getApplicationContext(),
android.Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
} else {
ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION},
REQUEST_LOCATION_ENABLE_CODE);
}
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