To reproduce:

1. Open the Qt Quick Controls 2 Gallery example or any other Qt Quick example that runs on Android.

2. Insert this code under ApplicationWindow in the main QML file:

FileDialog {
  title: "Please choose a file"
  folder: shortcuts.home
  onAccepted: { Qt.quit(); }
  onRejected: { Qt.quit(); }
  Component.onCompleted: { visible = true; }
}

 3. Compile with the standard GCC 4.9 toolchain and run on a real Android device (in reality the toolchain probably doesn't matter but I have only tested it with GCC 4.9).

4. At runtime the app will complain (and not start):

W Gallery : (null):0 ((null)): QQmlApplicationEngine failed to load component
W Gallery : (null):0 ((null)): qrc:/gallery.qml:61 Type FileDialog unavailable
W Gallery : file:///data/data/org.qtproject.example.gallery/qt-reserved-files/qml/QtQuick/Dialogs/DefaultFileDialog.qml:49 "qml": no such directory

I have verified that in the build folder where DefaultFileDialog.qml lives indeed the "qml" subdirectory is missing, whereas it's present in the Qt installation folder under. For some reason the androiddeployqt tool doesn't copy it over.