I'm having a similar problem, but I doubt that it really has got something to do with the request because my Stacktrace continues with a ClassCastException. I don't see how a Cast and a sent/read header should fit together.
It rather seems that this is another example of an JSF-Error Report that does not really provide us with the cause of the error.
PWC4011: Unable to set request character encoding to UTF-8 from context /SHK, because request parameters have already been read, or ServletRequest.getReader() has already been called
executePhase(RESTORE_VIEW 1,com.sun.faces.context.FacesContextImpl_at_bd567c) threw exception
java.lang.ClassCastException: javax.faces.component.UIViewRoot
at com.sun.faces.application.StateManagerImpl.restoreTree(StateManagerImpl.java:602)
at com.sun.faces.application.StateManagerImpl.restoreTree(StateManagerImpl.java:551)
at com.sun.faces.application.StateManagerImpl.restoreView(StateManagerImpl.java:87)
...
gruss -- stephan
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