Custom Error Message

Sometimes user wants to display custom error message instead of default message. For such cases ADF framework provides a way to create custom error handler class which extends default DCErrorHandlerImpl class. You are not required to write any code to register your custom exception handler class. Instead, you’ve to select the root node of the DataBindings.cpx files in the Structure window, and then use the Property Inspector to set the ErrorHandlerClass property to the fully qualified name of the error handler you want to use.

Example:
Default Message: JBO-25013 Too many object match primary key
CustomMessage: Duplicate Employee Id Found

Source: http://www.adftutorials.com/adf-custom-error-handler-to-display-custom-message-to-user.html