issued server command: /rg list
[18:43:50 WARN]: [WorldGuard] WorldGuard encountered an unexpected error
java.lang.NoSuchMethodError: com.google.common.base.Preconditions.checkState(ZLjava/lang/String;Ljava/lang/Object;)V
        at com.sk89q.worldguard.internal.guava.util.concurrent.Futures.getDone(Futures.java:1170) ~[worldguard-6.2.1.jar:?]
        at com.sk89q.worldguard.internal.guava.util.concurrent.Futures$4.run(Futures.java:1121) [worldguard-6.2.1.jar:?]
        at com.sk89q.worldguard.internal.guava.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:435) [worldguard-6.2.1.jar:?]
        at com.sk89q.worldguard.internal.guava.util.concurrent.AbstractFuture.executeListener(AbstractFuture.java:900) [worldguard-6.2.1.jar:?]
        at com.sk89q.worldguard.internal.guava.util.concurrent.AbstractFuture.complete(AbstractFuture.java:811) [worldguard-6.2.1.jar:?]
        at com.sk89q.worldguard.internal.guava.util.concurrent.AbstractFuture.set(AbstractFuture.java:653) [worldguard-6.2.1.jar:?]
        at com.sk89q.worldguard.internal.guava.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly(TrustedListenableFutureTask.java:111) [worldguard-6.2.1.jar:?]
        at com.sk89q.worldguard.internal.guava.util.concurrent.InterruptibleTask.run(InterruptibleTask.java:58) [worldguard-6.2.1.jar:?]
        at com.sk89q.worldguard.internal.guava.util.concurrent.TrustedListenableFutureTask.run(TrustedListenableFutureTask.java:75) [worldguard-6.2.1.jar:?]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_25]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_25]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_25]