Major Description
private org.apache.wicket.markup.MarkupStream org.apache.wicket.markup.MarkupException.markupStream [class=org.apache.wicket.markup.MarkupStream] <----- field that is not serializable
Exceptions have the contract of being serializable. That means, all their fields have to be serializable; otherwise you break that contract. I think for Wicket especially, it is important to respect and honor that contract. Therefore, MarkupException (or any other Wicket exceptions) should not contain any non-serializable objects in their fields. Either the markupException field should become transient or it should be replaced with a serializable view of it.