[Server thread/ERROR]: Couldn't save chunk; already in use by another instance of Minecraft?
net.minecraft.server.v1_9_R2.ExceptionWorldConflict: The save for world located at .\world_nether is being accessed from another location, aborting
	at net.minecraft.server.v1_9_R2.WorldNBTStorage.checkSession(WorldNBTStorage.java:78) ~[spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at net.minecraft.server.v1_9_R2.World.checkSession(World.java:2816) ~[spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at net.minecraft.server.v1_9_R2.ChunkRegionLoader.a(ChunkRegionLoader.java:124) ~[spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at net.minecraft.server.v1_9_R2.ChunkProviderServer.saveChunk(ChunkProviderServer.java:229) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at org.bukkit.craftbukkit.v1_9_R2.CraftWorld.unloadChunk0(CraftWorld.java:204) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at org.bukkit.craftbukkit.v1_9_R2.CraftWorld.unloadChunk(CraftWorld.java:192) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at org.bukkit.craftbukkit.v1_9_R2.CraftWorld.unloadChunk(CraftWorld.java:165) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at org.bukkit.craftbukkit.v1_9_R2.CraftWorld.unloadChunk(CraftWorld.java:161) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at org.bukkit.craftbukkit.v1_9_R2.CraftWorld.setKeepSpawnInMemory(CraftWorld.java:1242) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at com.onarandombox.MultiverseCore.MVWorld$3.set(MVWorld.java:134) [Multiverse-Core-2.5.jar:?]
	at com.onarandombox.MultiverseCore.MVWorld$3.set(MVWorld.java:129) [Multiverse-Core-2.5.jar:?]
	at me.main__.util.multiverse.SerializationConfig.SerializationConfig.flushPendingVPropChanges(SerializationConfig.java:248) [Multiverse-Core-2.5.jar:?]
	at com.onarandombox.MultiverseCore.WorldProperties.flushChanges(WorldProperties.java:374) [Multiverse-Core-2.5.jar:?]
	at com.onarandombox.MultiverseCore.MVWorld.<init>(MVWorld.java:90) [Multiverse-Core-2.5.jar:?]
	at com.onarandombox.MultiverseCore.MVWorld.<init>(MVWorld.java:57) [Multiverse-Core-2.5.jar:?]
	at com.onarandombox.MultiverseCore.utils.WorldManager.doLoad(WorldManager.java:476) [Multiverse-Core-2.5.jar:?]
	at com.onarandombox.MultiverseCore.utils.WorldManager.doLoad(WorldManager.java:447) [Multiverse-Core-2.5.jar:?]
	at com.onarandombox.MultiverseCore.utils.WorldManager.doLoad(WorldManager.java:422) [Multiverse-Core-2.5.jar:?]
	at com.onarandombox.MultiverseCore.utils.WorldManager.loadWorlds(WorldManager.java:725) [Multiverse-Core-2.5.jar:?]
	at com.onarandombox.MultiverseCore.MultiverseCore.onEnable(MultiverseCore.java:309) [Multiverse-Core-2.5.jar:?]
	at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:292) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:340) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:405) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at org.bukkit.craftbukkit.v1_9_R2.CraftServer.loadPlugin(CraftServer.java:362) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at org.bukkit.craftbukkit.v1_9_R2.CraftServer.enablePlugins(CraftServer.java:322) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at net.minecraft.server.v1_9_R2.MinecraftServer.t(MinecraftServer.java:416) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at net.minecraft.server.v1_9_R2.MinecraftServer.l(MinecraftServer.java:381) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at net.minecraft.server.v1_9_R2.MinecraftServer.a(MinecraftServer.java:336) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at net.minecraft.server.v1_9_R2.DedicatedServer.init(DedicatedServer.java:268) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at net.minecraft.server.v1_9_R2.MinecraftServer.run(MinecraftServer.java:532) [spigot-1.9.4.jar:git-Spigot-8a048fe-5ff377a]
	at java.lang.Thread.run(Unknown Source) [?:1.8.0_121]