Mac’s new OS X Yosemite upgrade has been causing problems with Dropbox. To fix these issues you must install the latest software update. This is a free update that can be done through the Mac app store located in your applications folder on your Mac.
It is always good to update your Mac, as issues arise within other programs and applications. You can set your Mac so it does this automatically. If you turn on the always update option your computer can restart and update when needed, when it does this it will re-open to how you left it and will be ready to continue on.
If you don’t want it to update whenever then the app store will just notify you when you have an update. It is recommended to do this when possible, as it will help your computer and programs to run smoothly and efficiently.