Android Failed to find style in current theme

I am assuming you copied your code from this StackOverflow answer. numberPickerStyle would be an attribute that is defined in your app. The code that you copied from the answer does not work. You would need to define an attribute in XML for the error to go away but that still would do nothing for you.

You can't style a NumberPicker. android:numberPickerStyle is private (see this issue).

Unfortunately, you can't style it. The styles and styling attributes for NumberPicker are not present in the public API, therefore you can't set them and change the default look. You can only select between light and dark theme. source