“java.lang.IllegalStateException: Attempt to validate an already invalid RegionSite” Error in ADF

Yesterday , I am working in region, I drag drop the table and so on.Suddenly i start getting this error -“java.lang.IllegalStateException: Attempt to validate an already invalid RegionSite”.

How to resolve this. Well there are many solution for this.

1. Check if the default activity is set on the taskflow included in the .jspx, if not try to set the default activity.
2. Check all bindings of page. if you not able to find it then delete it and create again.
3. Add the “-Djbo.debugoutput=console” in JAVA options of the Run/Debug/Profile to see the error
4. Check if all the library references for the UI project are proper and that is also accessible.
5. All The DB connection is available and active,the tables/views referenced are available in the D, All web services, if used, are active and accessible .