ClassCastException: WdVisibility ResourceMultiParentClassLoader

Hi

We have migrated WDJ dcs from 7.0 to & 7.3, most of the things are working fine except getting error as given below:

java.lang.ClassCastException: class com.sap.tc.webdynpro.progmodel.api.WDVisibility:service:tc~wd~webdynpro@com.sap.engine.boot.loader.ResourceMultiParentClassLoader@77a8994@alive incompatible with class java.lang.String:null

As per the error message it seems that visibility property of some UI element is assigned a null. But not able to find it.

Please help in resolving it asap.

Thanks In Advance

Akanksha