- Make sure there are no extra dots(..) in the name of the rgd file. (for example: "Wor.ld.rgd" should be "World.rgd")
If this does not fix the problem, the latest save file for that world might be corrupted. As a quickfix, you should be able restore an earlier version of the save by following these steps:
-Click Load World on Game Menu
-Open Save Folder Path
-Go to the "World" folder
-Go to the problematic save's folder
-Remove the folder that has "Latest" in the name.
-Try to load world again.