error thing

Caused by: java.lang.IllegalArgumentException: Cannot set to an empty path
        at org.apache.commons.lang.Validate.notEmpty(Validate.java:363)
        at org.bukkit.configuration.MemorySection.set(MemorySection.java:156)
        at org.bukkit.configuration.file.YamlConfiguration.convertMapsToSections(YamlConfiguration.java:78)
        at org.bukkit.configuration.file.YamlConfiguration.convertMapsToSections(YamlConfiguration.java:76)
        at org.bukkit.configuration.file.YamlConfiguration.convertMapsToSections(YamlConfiguration.java:76)
        at org.bukkit.configuration.file.YamlConfiguration.loadFromString(YamlConfiguration.java:66)
        at com.earth2me.essentials.EssentialsConf.load(EssentialsConf.java:147)
        at com.earth2me.essentials.UserData.reloadConfig(UserData.java:32)
        at com.earth2me.essentials.UserData.<init>(UserData.java:26)
        at com.earth2me.essentials.User.<init>(User.java:33)
        at com.earth2me.essentials.Essentials.getUser(Essentials.java:498)
        at com.earth2me.essentials.Essentials.getUser(Essentials.java:469)
        at com.earth2me.essentials.EssentialsPlayerListener.onPlayerMove(EssentialsPlayerListener.java:86)
        at sun.reflect.GeneratedMethodAccessor54.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:616)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302)
        ... 10 more
16:56:39 [SEVERE] Could not pass event PlayerMoveEvent to Essentials
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:304)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:460)
        at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:209)
        at net.minecraft.server.Packet10Flying.handle(SourceFile:126)
        at net.minecraft.server.NetworkManager.b(NetworkManager.java:229)
        at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:113)
        at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:567)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:459)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
Caused by: java.lang.IllegalArgumentException: Cannot set to an empty path
        at org.apache.commons.lang.Validate.notEmpty(Validate.java:363)
        at org.bukkit.configuration.MemorySection.set(MemorySection.java:156)
        at org.bukkit.configuration.file.YamlConfiguration.convertMapsToSections(YamlConfiguration.java:78)
        at org.bukkit.configuration.file.YamlConfiguration.convertMapsToSections(YamlConfiguration.java:76)
        at org.bukkit.configuration.file.YamlConfiguration.convertMapsToSections(YamlConfiguration.java:76)
        at org.bukkit.configuration.file.YamlConfiguration.loadFromString(YamlConfiguration.java:66)
        at com.earth2me.essentials.EssentialsConf.load(EssentialsConf.java:147)
        at com.earth2me.essentials.UserData.reloadConfig(UserData.java:32)
        at com.earth2me.essentials.UserData.<init>(UserData.java:26)
        at com.earth2me.essentials.User.<init>(User.java:33)
        at com.earth2me.essentials.Essentials.getUser(Essentials.java:498)
        at com.earth2me.essentials.Essentials.getUser(Essentials.java:469)
        at com.earth2me.essentials.EssentialsPlayerListener.onPlayerMove(EssentialsPlayerListener.java:86)
        at sun.reflect.GeneratedMethodAccessor54.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:616)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302)
        ... 10 more