Problem/Bug World Guard ''Could not load file''

Hello ! i have a HUGE problem ! I created my new server 1.8 - 1.12.2 and i instaslled WorldGuard. Beacause i really need this plugin ! But when i put in plugin and start the server it show me this :

Code:

[09:35:57 ERROR]: Could not load 'plugins\worldguard-6.2.1.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.NoClassDefFoundError: com/sk89q/minecraft/util/commands/CommandsManager
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:135) ~[spigot.jar:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329) ~[spigot.jar:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) [spigot.jar:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.craftbukkit.v1_8_R1.CraftServer.loadPlugins(CraftServer.java:291) [spigot.jar:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.DedicatedServer.init(DedicatedServer.java:152) [spigot.jar:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:505) [spigot.jar:git-Spigot-c3c767f-33d5de3]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_151]
Caused by: java.lang.NoClassDefFoundError: com/sk89q/minecraft/util/commands/CommandsManager
        at java.lang.Class.forName0(Native Method) ~[?:1.8.0_151]
        at java.lang.Class.forName(Unknown Source) ~[?:1.8.0_151]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[spigot.jar:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131) ~[spigot.jar:git-Spigot-c3c767f-33d5de3]
        ... 6 more
Caused by: java.lang.ClassNotFoundException: com.sk89q.minecraft.util.commands.CommandsManager
        at java.net.URLClassLoader.findClass(Unknown Source) ~[?:1.8.0_151]
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:101) ~[spigot.jar:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86) ~[spigot.jar:git-Spigot-c3c767f-33d5de3]
        at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_151]
        at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_151]
        at java.lang.Class.forName0(Native Method) ~[?:1.8.0_151]
        at java.lang.Class.forName(Unknown Source) ~[?:1.8.0_151]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[spigot.jar:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131) ~[spigot.jar:git-Spigot-c3c767f-33d5de3]
        ... 6 more

Anyone can help me ?
Server version : 1.8 - 1.12.2
Plugins : BuyCraftX , ChatFellings , Essentials-warp-gui , EssentialsX , HealtBar , KitAdder , Multiverse-Core , Multiverse-invertory , PermissionEX , PvPSoup , Vault , ViaVersion , and of course WorldGuard.
P.S i download the last file for WorldGuard , but when i download for 1.8 , same problem.