This message can occur during
holidays synchronization, if there are no more differences between the holidays of your holidays sets that are linked to one of the Holidays Sets of the
world holidays database, and the holidays of these linked holidays sets.
Note that, by default, many such differences are hidden.
You may wish to un-check the Hide Previously Kept Holidays and the Hide Previously Ignored Holidays checkboxes, to see all differences.
Topic 180960, last updated on 18-Apr-2020