Dropbox are changing how the Public Folder on older accounts work, on 15th March 2017 (“Dropbox-time”). This only affects users who signed up before 4 October 2012.
For Basic/Free users, your current public folder will become a normal secure folder. This means any current links to items in your public folder before the change over this week will no longer work. New shared links will need to be created, to enable sharing to continue.
This change will not effect Dropbox Plus, Pro and Business users until 1 September 2017.
