With Starbound 1.0 around the corner, it appears that old world files are not compatible with new world files. There is almost certainly going to be a full server wipe, sadly. The old world files will be available to download over FTP once we make the upgrade to Starbound 1.0. You may wish to keep a copy of the current version of Starbound if you want to review old worlds. There is an excellent guide here on how to backup your current version of Starbound: https://www.orionsedge.com/index.php?threads/important.1401/ Obviously you don't want to start building now, with 1.0 on the horizon.