OAF : Application: FND, Message Name: FND-INVALID APPLICATION. Tokens: APPL = null

How to fix this error :

Exception Details. 

          oracle.apps.fnd.framework.OAException: Application: FND, Message Name: FND-INVALID APPLICATION. Tokens: APPL = null; 

at oracle.apps.fnd.framework.webui.OAPageErrorHandler.prepareException(OAPageErrorHandler.java:1223) at oracle.apps.fnd.framework.webui.OAPageBean.preparePage(OAPageBean.java:1959) at oracle.apps.fnd.framework.webui.OAPageBean.preparePage(OAPageBean.java:501) at oracle.apps.fnd.framework.webui.OAPageBean.preparePage(OAPageBean.java:422) at OA.jspService(OA.jsp:40) at 


Solution : 

check the value of the product  xx.oracle.apps.product.requisition.server

product should be a valid application