Bug consol Group Manager

j'ai tout jour un bug dans la consol et jsp c'est lier a quoi

[17:04:39] [Server thread/ERROR]: Error occurred while disabling GroupManager v0.3.0 (Is it up to date?)
org.bukkit.plugin.IllegalPluginAccessException: Plugin attempted to register task while disabled
at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.validate(CraftScheduler.java:400) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.runTaskTimer(CraftScheduler.java:123) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.scheduleSyncRepeatingTask(CraftScheduler.java:119) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.scheduleSyncDelayedTask(CraftScheduler.java:102) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.anjocaido.groupmanager.events.GMSystemEvent.schedule(GMSystemEvent.java:52) ~[?:?]
at org.anjocaido.groupmanager.events.GroupManagerEventHandler.callEvent(GroupManagerEventHandler.java:39) ~[?:?]
at org.anjocaido.groupmanager.events.GroupManagerEventHandler.callEvent(GroupManagerEventHandler.java:64) ~[?:?]
at org.anjocaido.groupmanager.dataholder.WorldDataHolder.reloadGroups(WorldDataHolder.java:470) ~[?:?]
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.saveChanges(WorldsHolder.java:354) ~[?:?]
at org.anjocaido.groupmanager.GroupManager.onDisable(GroupManager.java:107) ~[?:?]
at org.anjocaido.groupmanager.GroupManager.onDisable(GroupManager.java:82) ~[?:?]
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:323) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.plugin.java.JavaPluginLoader.disablePlugin(JavaPluginLoader.java:364) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.plugin.SimplePluginManager.disablePlugin(SimplePluginManager.java:424) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.plugin.SimplePluginManager.disablePlugins(SimplePluginManager.java:417) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.plugin.SimplePluginManager.clearPlugins(SimplePluginManager.java:458) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.reload(CraftServer.java:708) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.Bukkit.reload(Bukkit.java:535) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:25) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:641) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchServerCommand(CraftServer.java:627) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at net.minecraft.server.v1_8_R3.DedicatedServer.aO(DedicatedServer.java:412) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:375) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_202]

et aussie quand je veux mettre des permmisino au grade sa ne marche pas