Копирни папку region и level.dat. Остальное лучше не трогать.
Поменял местами данные файлы у миров. Сервер закрылся.
[SPOILER="[17:27:50] [main/INFO]:
[17:28:52] [Server thread/INFO]: Stopping server
[17:28:52] [Server thread/INFO]: Saving players
[17:28:52] [Server thread/INFO]: Saving worlds
[17:28:52] [Server thread/INFO]: Saving chunks for level 'world'/Overworld
[17:28:53] [Server thread/ERROR]: Exception stopping the server
java.lang.IllegalArgumentException: Could not get provider type for dimension 8, does not exist
at net.minecraftforge.common.DimensionManager.getProviderType(DimensionManager.java:178) ~[DimensionManager.class:1.7.10-1614.58]
at net.minecraftforge.common.DimensionManager.shouldLoadSpawn(DimensionManager.java:448) ~[DimensionManager.class:1.7.10-1614.58]
at net.minecraft.world.gen.ChunkProviderServer.func_73241_b(ChunkProviderServer.java:134) ~[ms.class:?]
at net.minecraft.world.WorldServer.func_73044_a(WorldServer.java:1102) ~[mt.class:?]
at net.minecraft.server.MinecraftServer.func_71267_a(MinecraftServer.java:538) ~[MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.func_71260_j(MinecraftServer.java:594) ~[MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:755) [MinecraftServer.class:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_144]
[17:28:53] [Server thread/INFO]: Applying holder lookups
[17:28:53] [Server thread/INFO]: Holder lookups applied
[17:28:53] [Server thread/INFO]: The state engine was in incorrect state SERVER_STOPPING and forced into state SERVER_STOPPED. Errors may have been discarded.
[/SPOILER]
