Dropbox sync fails with a 504 error
Article ID: 548 | Last Updated: Sun, Oct 14, 2012 at 3:08 PM
A 504 error from Dropbox is returned in case the server timed out on your request (due to network contention or their servers experiencing heavy load). This can even happen in case Dropbox has blocked access to your account in case they feel their server is being abused by too much traffic.
A solution is to try again after a little while. If the problem persists your best bet still is to contact support at Dropbox as they are the only ones able to help unfortunately:
Print Article