DAJ649E A "U" command can only be entered on a DSNACCOX exception condition that is currently selected (displayed in white).

Explanation
The U (update) line command was entered next to a selectable
exception condition that is not a DSNACCOX-like exception. The U command can
only be used for updating a currently selected DSNACCOX-like exception that is shown in white.

User response
Clear the line command from the selection area.