World Guard ERROR

Spigot Version: git-Spigot-db6de12-18fbb24 (MC: 1.8.8)
World Guard Version: WorldGuard 6.2.1;84bc322


Error:
[12:26:25 WARN]: [WorldGuard] WorldGuard encountered an unexpected error
java.lang.NoSuchMethodError: com.google.common.base.Preconditions.checkState(ZLjava/lang/String;Ljava/lang/ObjectV
at com.sk89q.worldguard.internal.guava.util.concurrent.Futures.getDone(Futures.java:1170) ~[WorldGuard.jar:?]
at com.sk89q.worldguard.internal.guava.util.concurrent.Futures$4.run(Futures.java:1121) [WorldGuard.jar:?]
at com.sk89q.worldguard.internal.guava.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:435) [WorldGuard.jar:?]
at com.sk89q.worldguard.internal.guava.util.concurrent.AbstractFuture.executeListener(AbstractFuture.java:900) [WorldGuard.jar:?]
at com.sk89q.worldguard.internal.guava.util.concurrent.AbstractFuture.complete(AbstractFuture.java:811) [WorldGuard.jar:?]
at com.sk89q.worldguard.internal.guava.util.concurrent.AbstractFuture.set(AbstractFuture.java:653) [WorldGuard.jar:?]
at com.sk89q.worldguard.internal.guava.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly(TrustedListenableFutureTask.java:111) [WorldGuard.jar:?]
at com.sk89q.worldguard.internal.guava.util.concurrent.InterruptibleTask.run(InterruptibleTask.java:58) [WorldGuard.jar:?]
at com.sk89q.worldguard.internal.guava.util.concurrent.TrustedListenableFutureTask.run(TrustedListenableFutureTask.java:75) [WorldGuard.jar:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_131]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_131]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_131]
[12:26:25 INFO]: Failed to fetch region list: WorldGuard: An unexpected error occurred! Please see the server console.


Thanks!

 

All commands of worldguard print this error :/

 

/rg define /rg create /rg list.... All

 

Why I cant use 6.2.1? Bugged?

 

Oh my bad then... Thanks @AgainstTheNight