There is no excuse for Dropbox features failing. When trying to move the default Dropbox folder from C:\Users\Name\Dropbox to a better location, Dropbox is failing when File Explorer happens to be open in a contained folder. The poor user is left high and dry, with no useful error message. It can take a lot of Web searching to find the answer.
1. Make the move work by asking the user if it is okay for File Explorer to be closed, then closing it.
2. Inform the user that File Explorer needs to be closed before Dropbox can be moved.