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I got a pb, i did a map on vanilla version and some saves of it. But when i change the version to CraftBukkit and I refresh the save on the server it turns it to Vanilla back again. I would like to keep the vanilla map but turn the version to Bukkit, is it possible ? 
Ty bye
Shut your server down, go to the software page and install bukkit.
You can keep the map of course.
But please note, that you can not switch from a 1.13 server to an older version.
