The hell? Such a vague error message!
All you really needed to say is that the width of the image must be even, as (not so clearly) stated by the documentation.
Once that's worked out you should be getting faces again.
public FaceDetector (int width, int height, int maxFaces)
Creates a FaceDetector, configured with the size of the images to be analysed and the maximum number of faces that can be detected. These parameters cannot be changed once the object is constructed. Note that the width of the image must be even.
the width of the image
the height of the image
the maximum number of faces to identify