I get a error when I run the plugin

[Jok3rTV]

[01:26:01 ERROR]: Error occurred while enabling DamageIndicator v1.3.7 (Is it up to date?)
java.lang.ExceptionInInitializerError
at com.comphenix.protocol.injector.netty.InjectionFactory.fromPlayer(InjectionFactory.java:93) ~[?:?]
at com.comphenix.protocol.injector.netty.ProtocolInjector$4.injectPlayer(ProtocolInjector.java:371) ~[?:?]
at com.comphenix.protocol.injector.PacketFilterManager.initializePlayers(PacketFilterManager.java:946) ~[?:?]
at com.comphenix.protocol.injector.PacketFilterManager.incrementPhases(PacketFilterManager.java:462) ~[?:?]
at com.comphenix.protocol.injector.PacketFilterManager.addPacketListener(PacketFilterManager.java:396) ~[?:?]
at cl.mastercode.DamageIndicator.util.EntityHider.(EntityHider.java:87) ~[?:?]
at cl.mastercode.DamageIndicator.listener.DamageIndicatorListener.reload(DamageIndicatorListener.java:83) ~[?:?]
at cl.mastercode.DamageIndicator.listener.DamageIndicatorListener.(DamageIndicatorListener.java:71) ~[?:?]
at cl.mastercode.DamageIndicator.DIMain.reload(DIMain.java:53) ~[?:?]
at cl.mastercode.DamageIndicator.DIMain.onEnable(DIMain.java:66) ~[?:?]
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:321) ~[server.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:340) [server.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:405) [server.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugin(CraftServer.java:357) [server.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.enablePlugins(CraftServer.java:317) [server.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.reload(CraftServer.java:741) [server.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.Bukkit.reload(Bukkit.java:535) [server.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:25) [server.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) [server.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:641) [server.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.PlayerConnection.handleCommand(PlayerConnection.java:1162) [server.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:997) [server.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:45) [server.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:1) [server.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [server.jar:git-Spigot-db6de12-18fbb24]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_275]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_275]
at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [server.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:715) [server.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [server.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [server.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [server.jar:git-Spigot-db6de12-18fbb24]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_275]
Caused by: java.lang.IllegalArgumentException: 'PROTOCOL-0' is already in use
at io.netty.util.UniqueName.(UniqueName.java:53) ~[server.jar:git-Spigot-db6de12-18fbb24]
at io.netty.util.AttributeKey.(AttributeKey.java:47) ~[server.jar:git-Spigot-db6de12-18fbb24]
at io.netty.util.AttributeKey.valueOf(AttributeKey.java:39) ~[server.jar:git-Spigot-db6de12-18fbb24]
at com.comphenix.protocol.injector.netty.ChannelInjector.(ChannelInjector.java:86) ~[?:?]
... 33 more