To unlock your Dropbox account, simply open Dropbox and log in with your user credentials. If you have received an error message that a file is locked or in use when you attempted to upload the file to Dropbox, the file is either open in a running application, the file has an attribute of “Read-Only” in Windows or “Locked” on Mac, or the Dropbox folder is not configured correctly with your credentials in the Mac Sharing & Permissions folder settings. Note that the locked local files issue is a known issue with uploading files to Dropbox from Mac OS X 10.1 and higher. Writer Bio

How to Unlock a Dropbox - 90