Signals that a serialization-related method has been invoked in the wrong place. Some methods in ObjectInputStream and ObjectOutputStream can only be called from a nested call to readObject() or writeObject(). Any attempt to call them from another context will cause a NotActiveException to be thrown. The list of methods that are protected this way is:

• ObjectInputStream.DefaultReadObject
• ObjectInputStream.RegisterValidation(IObjectInputValidation, System.Int32)
• ObjectOutputStream.DefaultWriteObject

[Android Documentation]