a0d929ca_WSRP_v2_0_Specification__Statement_text
[#] CS080 [Section] 5.4.3 [Statement text] 
If the Producer implements access control that prevents Portlets from updating persistent state and a Portlet is unable to process the interaction without such an update, then the fault PortletStateChangeRequired MAY be thrown indicating the interaction processing failed.
WSRP v2.0 Specification
Statement text