Have been looking around for a general strategy that for adding an error page to an ADF Application. found there options
Option 1 : make html error pages for each type of exception
Option 2 : make one error page and generalized bean
Option 3 : Make one error page, One task flow for it , In all the managaed beans inside try catch do add return "error_page_task_flow"
Different approaches may be useful in different scenarious