End group cannot be empty unless both the Start and Progress groups are also empty
You have removed all installation dialog boxes from the End node in the User Interface Editor, but there are still installation dialog boxes in the Start or Progress nodes. If any installation dialog boxes are displayed during installation, the Finished dialog box must be displayed and must be the last dialog box in the End node.
To correct this error
In the User Interface Editor, select the End node.
On the Action menu, choose Add Dialog.
In the Add Dialog dialog box, select the Finished dialog box.
If the Finished dialog box was moved to a different node, it will not appear in the Add Dialog dialog box. In this case, you can move it to the End node by using a drag-and-drop operation or the Cut and Paste commands.
If you do not want to display a user interface during installation:
In the User Interface Editor, select any remaining dialog boxes and delete them.