Minecraft wiki entry for Saved_data_Dropbox_guide, associated text: If you wish to sync your Minecraft files between different operating systems, you need to add a few extra steps to the method above. This is because the bin folder inside your minecraft folder, which contains binary files which run the program (as opposed to data files, like your saved games) has different files depending on your operating system. These files, however, have no overlap, and you can have a fully operational Minecraft folder for all operating systems (Windows, Mac OS and Linux). There are no known problems arising from different versions of the same operating system.