fwiw, he view scope is in JSF 2.0

 

You need to make sure your managed bean implements Serailizable ... if you have members of your class that do not implement serializable you need to provide custom state management methods in your class (saveState and restoreState for example) to handled writing out a serializable plain object so the runtime can save the state of your bean during the renderResponse phase.

I've been facing the same troubles with a bean stored in ViewScope. As Jeremy suggested it was caused by the member variable that holds the Notes document (lotus.domino.Document) as that class does not implement Serializable interface.

For so far I decided not to keep notes document as member variable and use universalID instead. After this change the bean works fine.