Adjusting Enhancements After an Upgrade 
You can edit an enhancement of a Web Dynpro ABAP object after an upgrade using the Adjustment Tools of the Enhancement Builder. Usually no other actions are required, but if an enhanced component is changed in the original system and the change is imported into the system where the enhancement is, this could lead to a conflict.
The following types of conflict are possible:
Name collision
Reference to an element deleted in the original system
The adjustment tool has specific functions to handle each type of conflict:
Name collisions: Functions for renaming or deleting names
Reference to a deleted (parent) object: Function for deleting object
The adjustment tool also allows you to compare the original component (at the time of the enhancement) with the new imported version.
More information: Performing Adjustments
Name Collision
A name collision can occur with the following objects:
In a controller:
Context nodes
Context attributes
Controller attributes
Methods
In a view
UI elements
Actions
In a view or a window
Inbound plugs
Outbound plugs
In a component
Component usage
Reference to Elements Deleted in the Original System
Changes must be made to references to the following objects when they are deleted in the original system:
In a controller:
Pre/post exits of deleted methods
Deleted parent nodes (for context nodes and attributes)
Context mapping: deleted mapping target, deleted controller usage
In a view:
Deleted parent UI elements
Deleted context attributes in the binding
Deleted action (event binding)
In a window:
With navigation links: plug deleted, embedding deleted
When a complete controller is deleted
When a complete view is deleted
When a complete window is deleted
When a complete component is deleted