If you override onCreateDialog with AlertDialog instead of overriding onCreateView, you shall bump into IllegalStateException: Fragment does not have a view when calling getChildFragmentManager.
To solve this issue, make sure to override onCreateView to return the view created in onCreateDialog.
class LocationPickerDialog : DialogFragment() { lateinit var customView: View override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? { return customView } override fun onCreateDialog(savedInstanceState: Bundle?): Dialog { Log.d(TAG, "onCreateDialog") // StackOverflowError // customView = layoutInflater.inflate(R.layout.dialog_location_picker, null) customView = activity!!.layoutInflater.inflate(R.layout.dialog_location_picker, null) val builder = AlertDialog.Builder(context!!) .setView(customView) .setPositiveButton(android.R.string.ok) { _, _ -> // do something } .setNegativeButton(android.R.string.cancel) { _, _ -> // do something } val dialog = builder.create() return dialog } override fun onActivityCreated(savedInstanceState: Bundle?) { // if onCreateView doesn't return a view // java.lang.IllegalStateException: Fragment does not have a view mapFragment = childFragmentManager.findFragmentByTag("map") as SupportMapFragment? }}