CameraX doesn't save the pictures

Question

I'm trying to use the example app from google codelabs to implement the camerax application, but i dont know, why it doesnt save the pictures correctly.

private fun takePhoto() {
    // Get a stable reference of the modifiable image capture use case
    val imageCapture = imageCapture ?: return

    // Create time-stamped output file to hold the image
    val photoFile = File(
        outputDirectory,
        SimpleDateFormat(
            FILENAME_FORMAT, Locale.GERMAN
        ).format(System.currentTimeMillis()) + ".jpg"
    )

    // Create output options object which contains file + metadata
    val outputOptions = ImageCapture.OutputFileOptions.Builder(photoFile).build()

    // Set up image capture listener, which is triggered after photo has
    // been taken
    imageCapture.takePicture(
        outputOptions,
        ContextCompat.getMainExecutor(this),
        object : ImageCapture.OnImageSavedCallback {
            override fun onError(exc: ImageCaptureException) {
                Log.e(TAG, "Photo capture failed: ${exc.message}", exc)
            }

            override fun onImageSaved(output: ImageCapture.OutputFileResults) {
                val savedUri = Uri.fromFile(photoFile)
                val msg = "Photo capture succeeded: $savedUri"
                Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
                Log.d(TAG, msg)
            }
        })
}

This is the takePhoto() function which should take and save the photo.

EDIT:

This is the whole code, without imports.

The Emulator is the Pixel 3a XL API 30

class MainActivity : AppCompatActivity() {

//CameraX Elements:
private var preview: Preview? = null
private var imageCapture: ImageCapture? = null
private var camera: Camera? = null

//File Elements
private lateinit var outputDirectory: File

//View Elements
//private lateinit var camera_capture_button: Button
private lateinit var cameraExecutor: ExecutorService


override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    // Request camera permissions
    if (allPermissionsGranted()) {
        startCamera()
    } else {
        ActivityCompat.requestPermissions(
            this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS)
    }

    // Set up the listener for take photo button
    camera_capture_button.setOnClickListener { takePhoto() }

    outputDirectory = getOutputDirectory()

    cameraExecutor = Executors.newSingleThreadExecutor()
}

private fun takePhoto() {
    // Get a stable reference of the modifiable image capture use case
    val imageCapture = imageCapture ?: return

    // Create time-stamped output file to hold the image
    val photoFile = File(
        outputDirectory,
        SimpleDateFormat(
            FILENAME_FORMAT, Locale.GERMAN
        ).format(System.currentTimeMillis()) + ".jpg"
    )

    // Create output options object which contains file + metadata
    val outputOptions = ImageCapture.OutputFileOptions.Builder(photoFile).build()

    // Set up image capture listener, which is triggered after photo has
    // been taken
    imageCapture.takePicture(
        outputOptions,
        ContextCompat.getMainExecutor(this),
        object : ImageCapture.OnImageSavedCallback {
            override fun onError(exc: ImageCaptureException) {
                Log.e(TAG, "Photo capture failed: ${exc.message}", exc)
            }

            override fun onImageSaved(output: ImageCapture.OutputFileResults) {
                val savedUri = Uri.fromFile(photoFile)
                val msg = "Photo capture succeeded: $savedUri"
                Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
                Log.d(TAG, msg)
            }
        })
}

private fun startCamera() {
    val cameraProviderFuture = ProcessCameraProvider.getInstance(this)

    cameraProviderFuture.addListener(Runnable {
        // Used to bind the lifecycle of cameras to the lifecycle owner
        val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

        // Preview
        val preview = Preview.Builder()
            .build()
            .also {
                it.setSurfaceProvider(viewFinder.surfaceProvider)
            }

        // Select back camera as a default
        val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

        try {
            // Unbind use cases before rebinding
            cameraProvider.unbindAll()

            // Bind use cases to camera
            cameraProvider.bindToLifecycle(
                this, cameraSelector, preview)

        } catch(exc: Exception) {
            Log.e(TAG, "Use case binding failed", exc)
        }

    }, ContextCompat.getMainExecutor(this))
}

override fun onRequestPermissionsResult(
    requestCode: Int, permissions: Array<String>, grantResults:
    IntArray) {
    if (requestCode == REQUEST_CODE_PERMISSIONS) {
        if (allPermissionsGranted()) {
            startCamera()
        } else {
            Toast.makeText(this,
                "Permissions not granted by the user.",
                Toast.LENGTH_SHORT).show()
            finish()
        }
    }
}

private fun allPermissionsGranted() = REQUIRED_PERMISSIONS.all {
    ContextCompat.checkSelfPermission(
        baseContext, it) == PackageManager.PERMISSION_GRANTED
}

private fun getOutputDirectory(): File {
    val mediaDir = externalMediaDirs.firstOrNull()?.let{
        File(it, resources.getString(R.string.app_name)).apply{mkdirs()}}
    return if(mediaDir != null && mediaDir.exists())
        mediaDir
    else
        filesDir
    }

companion object {
    private const val TAG = "CameraXBasic"
    private const val FILENAME_FORMAT = "yyyy-MM-dd-HH-mm-ss-SSS"
    private const val REQUEST_CODE_PERMISSIONS = 10
    private val REQUIRED_PERMISSIONS = arrayOf(android.Manifest.permission.CAMERA)
    }

}

The Log after pressing take Photo:

2021-05-25 14:41:23.473 548-1359/system_process I/system_server: oneway function results will be dropped but finished with status OK and parcel size 4