2146087 - java.lang.IllegalAccessError while navigating in EP

After upgrading EP to some certain SPs, you are facing 500 internal server error while navigating in Enterprise Portal.
You can find below error in server defaultTrace:
"
Cannot process an HTTP request to servlet [prt] in [irj] web application.
[EXCEPTION]
java.lang.IllegalAccessError: tried to access field com.sap.portal.prt.component.CachablePortalComponent.INVALIDATE_EVENT_TYPE (class loader service:tc~epbc~prtc~core@61990, resolved service:tc~epbc~prtc~core@61990) from class com.sapportals.portal.prt.service.hook.CacheInvalidatorHookService (class loader WCE_PRIVATE_CL_sap.com/com.sap.portal.runtime.system.hooks@396849)
 at com.sapportals.portal.prt.service.hook.CacheInvalidatorHookService.doEventHook(CacheInvalidatorHookService.java:19)
 at com.sapportals.portal.prt.connection.PortalHook.doEventHook(PortalHook.java:227)
 at com.sap.portal.prt.pom.PortalNode.fireEventOnNode(PortalNode.java:337)
 at com.sap.portal.prt.core.PortalRequestManager.runRequestCycle(PortalRequestManager.java:484)
 at com.sapportals.portal.prt.connection.ServletConnection._handleRequest(ServletConnection.java:224)
....
"

• SAP NetWeaver 7.4 SP10
• SAP enhancement package 1 for SAP NetWeaver 7.3 SP14

Enterprise Portal, EP, IllegalAccessError, 500 internal server error, EP BASIS API , KBA , EP-PIN-PRT , Portal Runtime , Problem