Please help in GroupManager.

Please help me solve this error for GroupManager plugin.
This is what it said, please help
=============================== GM ERROR LOG ===============================
= ERROR REPORT START - 2.1.28 (Phoenix) =

java.lang.IllegalArgumentException: The following file couldn't pass on Parser.
plugins\GroupManager\worlds\world\users.yml
at org.anjocaido.groupmanager.dataholder.WorldDataHolder.loadUsers(WorldDataHolder.java:852)
at org.anjocaido.groupmanager.dataholder.WorldDataHolder.loadUsers(WorldDataHolder.java:527)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.loadWorld(WorldsHolder.java:684)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.loadWorld(WorldsHolder.java:640)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.initialWorldLoading(WorldsHolder.java:110)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.initialLoad(WorldsHolder.java:100)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.resetWorldsHolder(WorldsHolder.java:92)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.<init>(WorldsHolder.java:59)
at org.anjocaido.groupmanager.GroupManager.onEnable(GroupManager.java:179)
at org.anjocaido.groupmanager.GroupManager.onEnable(GroupManager.java:103)
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:217)
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:457)
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:381)
at org.bukkit.craftbukkit.v1_7_R1.CraftServer.loadPlugin(CraftServer.java:298)
at org.bukkit.craftbukkit.v1_7_R1.CraftServer.enablePlugins(CraftServer.java:280)
at net.minecraft.server.v1_7_R1.MinecraftServer.m(MinecraftServer.java:338)
at net.minecraft.server.v1_7_R1.MinecraftServer.g(MinecraftServer.java:315)
at net.minecraft.server.v1_7_R1.MinecraftServer.a(MinecraftServer.java:275)
at net.minecraft.server.v1_7_R1.DedicatedServer.init(DedicatedServer.java:175)
at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:420)
at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617)
Caused by: unacceptable character '?' (0xFFFD) special characters are not allowed
in "<reader>", position 415
at org.yaml.snakeyaml.reader.StreamReader.checkPrintable(StreamReader.java:98)
at org.yaml.snakeyaml.reader.StreamReader.update(StreamReader.java:191)
at org.yaml.snakeyaml.reader.StreamReader.<init>(StreamReader.java:63)
at org.yaml.snakeyaml.Yaml.load(Yaml.java:423)
at org.anjocaido.groupmanager.dataholder.WorldDataHolder.loadUsers(WorldDataHolder.java:847)
... 20 more

 

Caused by: unacceptable character '?' (0xFFFD) special characters are not allowed
You edited the config somewhere and added a '?'.
Weather you did this in-game or in the files it needs to be changed.
Try backing up, then deleting the config. Reload the plugin and see if the error is fixed. If not look for another issue.
The error is about a '?' being where is shouldn't be.

 

Just expanding on what SleepyDog said, the exact file with the problem in it is your users.yml found at plugins\GroupManager\worlds\world\users.yml . So it isn't the config file, it is the file that stores your GroupManager users information.