ERROR

[20:39:23 ERROR]: Couldn't save chunk; already in use by another instance of Minecraft?
net.minecraft.server.v1_8_R3.ExceptionWorldConflict: The save for world located at ./ares_2 is being accessed from another location, aborting
        at net.minecraft.server.v1_8_R3.WorldNBTStorage.checkSession(WorldNBTStorage.java:72) ~[spigot-latest.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.World.checkSession(World.java:2824) ~[spigot-latest.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.ChunkRegionLoader.a(ChunkRegionLoader.java:120) ~[spigot-latest.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.ChunkProviderServer.saveChunk(ChunkProviderServer.java:251) [spigot-latest.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.ChunkProviderServer.unloadChunks(ChunkProviderServer.java:357) [spigot-latest.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.WorldServer.doTick(WorldServer.java:234) [spigot-latest.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:770) [spigot-latest.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigot-latest.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot-latest.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot-latest.jar:git-Spigot-db6de12-18fbb24]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_101]