The message is ''not'' an error message. There is no need for regular editors to take action with respect to this message. The message and this category are being used to track instances of certain citation templates that use with a value of .
This is a tracking category for CS1 citations
that use . That parameter is now supplied by default by CS1 templates, so can safely be removed from CS1 citation templates without affecting functionality.
Pages in this category should only be added by Module:Citation/CS1