I have migrated from JSF 1.2 to 2.0. In my app I have a managed bean in application scope which holds references to some immutable objects of the class named SearchCategory. SearchCategory only has a few final variables which are set via constructor parameters. In fact SearchCategory does not have a zero-parameter constructor. Now, when validation fails for the view where SearchCategory instances are shown the second request results in a InstantiationException because StateHolderSaver calls Class#newInstance(). And as I said before SearchCategory does not provide a zero-parameter constructor. Isn't it a bug that StateHolderSaver relies on classes having a zero-parameter constructor? In JSF 1.2 I was just fine without this zero-parameter constructor. Are there any guidelines for classes potentially being saved and restored by JSF? If yes, where are these documented/specified? Has this something to do with the new partial state saving mechanism?