[Help]: D/BluetoothLeScanner( 4064): could not find callback wrapper

[Rizza-Rabe]

Requirements

• I've looked at the README 'Common Problems' section

Have you checked this problem on the example app?

Yes

FlutterBluePlus Version

1.31.12

Flutter Version

3.10.6

What OS?

Android

OS Version

Android 13.

Bluetooth Module

AT-09 BLE

What is your problem?

Does not show devices. Always throw: could not find callback wrapper

Logs

I/BluetoothAdapter( 4064): STATE_ON
I/BluetoothAdapter( 4064): STATE_ON
D/BluetoothLeScanner( 4064): could not find callback wrapper

[chipweinberger]

show more logs from the example app.

D/BluetoothLeScanner( 4064): could not find callback wrapper

the is a debug log. It means you are calling stopScan, but no scan is currently in progress.

https://stackoverflow.com/questions/40862767/bluetoothlescanner-could-not-find-callback-wrapper

[chipweinberger]

https://copyprogramming.com/howto/android-btle-cannot-find-callback-wrapper#android-btle-cannot-find-callback-wrapper

check your permissions?

https://community.wildernesslabs.co/t/bluetooth-devices-not-found/1649/2

dotintent/FlutterBleLib#622

[Rizza-Rabe]

if (await Permission.bluetoothScan.isDenied) {
      await Permission.bluetoothScan.request();
    }
    if (await Permission.bluetoothConnect.isDenied) {
      await Permission.bluetoothConnect.request();
    }
    if (await Permission.location.isDenied) {
      await Permission.location.request();
    }

    var subscription = FlutterBluePlus.onScanResults.listen((result) {
      Utility().printLog("OnScanResult: $result");
    });

    FlutterBluePlus.cancelWhenScanComplete(subscription);

    await FlutterBluePlus.startScan(
      timeout: const Duration(seconds: 10),
    );

[Rizza-Rabe]

Im unable to get some devices.

[Rizza-Rabe]

D/[FBP-Android](14010): [FBP] onMethodCall: startScan
I/ViewRootImpl@1c09fe3[MainActivity](14010): MSG_WINDOW_FOCUS_CHANGED 0 0
I/ViewRootImpl@1c09fe3[MainActivity](14010): stopped(false) old = false
I/DecorView(14010): notifyKeepScreenOnChanged: keepScreenOn=false
I/MSHandlerLifeCycle(14010): removeMultiSplitHandler: no exist. decor=DecorView@866de74[MainActivity]
I/ViewRootImpl@1c09fe3[MainActivity](14010): performTraversals params={(0,0)(fillxfill) sim={adjust=resize forwardNavigation} ty=BASE_APPLICATION fmt=TRANSLUCENT wanim=0x1030001
I/ViewRootImpl@1c09fe3[MainActivity](14010):   fl=81810100
I/ViewRootImpl@1c09fe3[MainActivity](14010):   pfl=12020040
I/ViewRootImpl@1c09fe3[MainActivity](14010):   vsysui=500
I/ViewRootImpl@1c09fe3[MainActivity](14010):   bhv=DEFAULT
I/ViewRootImpl@1c09fe3[MainActivity](14010):   fitSides= naviIconColor=0}
I/ViewRootImpl@1c09fe3[MainActivity](14010): performTraversals mFirst=false windowShouldResize=false viewVisibilityChanged=false mForceNextWindowRelayout=false params={(0,0)(fillxfill) sim={adjust=resize forwardNavigation} ty=BASE_APPLICATION fmt=TRANSLUCENT wanim=0x1030001
I/ViewRootImpl@1c09fe3[MainActivity](14010):   fl=81810100
I/ViewRootImpl@1c09fe3[MainActivity](14010):   pfl=12020040
I/ViewRootImpl@1c09fe3[MainActivity](14010):   vsysui=500
I/ViewRootImpl@1c09fe3[MainActivity](14010):   bhv=DEFAULT
I/ViewRootImpl@1c09fe3[MainActivity](14010):   fitSides= naviIconColor=0}
I/ViewRootImpl@1c09fe3[MainActivity](14010): updateBlastSurfaceIfNeeded mBlastBufferQueue=0xb40000775b660c00 isSameSurfaceControl=true
I/BLASTBufferQueue(14010): update, w= 1080 h= 2408 mName = ViewRootImpl@1c09fe3[MainActivity] mNativeObject= 0xb40000775b660c00 sc.mNativeObject= 0xb4000077c7b187a0 format= -3 caller= android.view.ViewRootImpl.updateBlastSurfaceIfNeeded:2898 android.view.ViewRootImpl.relayoutWindow:9847 android.view.ViewRootImpl.performTraversals:3884 android.view.ViewRootImpl.doTraversal:3116 android.view.ViewRootImpl$TraversalRunnable.run:10885 android.view.Choreographer$CallbackRecord.run:1301 
I/ViewRootImpl@1c09fe3[MainActivity](14010): Relayout returned: old=(0,0,1080,2408) new=(0,0,1080,2408) req=(1080,2408)0 dur=10 res=0x0 s={true 0xb4000077d1226000} ch=false seqId=0
I/ViewRootImpl@1c09fe3[MainActivity](14010): updateBoundsLayer: t = android.view.SurfaceControl$Transaction@5689421 sc = Surface(name=Bounds for - com.zz.arduino.training.pad.training_pad/com.zz.arduino.training.pad.training_pad.MainActivity@1)/@0xdcdc791 frame = 3
I/ViewRootImpl@1c09fe3[MainActivity](14010): mWNT: t=0xb40000775b78c200 mBlastBufferQueue=0xb40000775b660c00 fn= 3 caller= android.view.ViewRootImpl.prepareSurfaces:2985 android.view.ViewRootImpl.performTraversals:4233 android.view.ViewRootImpl.doTraversal:3116 
I/ViewRootImpl@1c09fe3[MainActivity](14010): MSG_WINDOW_FOCUS_CHANGED 1 0
I/ViewRootImpl@1c09fe3[MainActivity](14010): mThreadedRenderer.initializeIfNeeded()#2 mSurface={isValid=true 0xb4000077d1226000}
D/InputMethodManager(14010): startInputInner - Id : 0
I/InputMethodManager(14010): startInputInner - mService.startInputOrWindowGainedFocus
D/[FBP-Android](14010): [FBP] onMethodCall: stopScan
I/BluetoothAdapter(14010): STATE_ON
I/BluetoothAdapter(14010): STATE_ON
D/BluetoothLeScanner(14010): could not find callback wrapper

[chipweinberger]

use example app.

[chipweinberger]

any updates. theres not much actionable here.

[Xelopakson]

did you fix this ?

[chipweinberger]

there's nothing to fix. BluetoothLeScanner: could not find callback wrapper just means you are calling stopScan but there is no scan currently in progress.

https://stackoverflow.com/questions/40862767/bluetoothlescanner-could-not-find-callback-wrapper

---

that said, I added a fix with a better log message: 69ccb70