[16:29:47] [Server thread/WARN]: [ProjectKorra] Task #32 for ProjectKorra v1.8.0 BETA 5 generated an exception
java.util.ConcurrentModificationException
    at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429) ~[?:1.8.0_60]
    at java.util.HashMap$KeyIterator.next(HashMap.java:1453) ~[?:1.8.0_60]
    at com.projectkorra.projectkorra.util.RevertChecker.revertEarthBlocks(RevertChecker.java:46) ~[?:?]
    at com.projectkorra.projectkorra.earthbending.EarthbendingManager.run(EarthbendingManager.java:20) ~[?:?]
    at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftTask.run(CraftTask.java:71) ~[bending.jar:git-Spigot-76236cb-c373061]
    at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:350) [bending.jar:git-Spigot-76236cb-c373061]
    at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:723) [bending.jar:git-Spigot-76236cb-c373061]
    at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [bending.jar:git-Spigot-76236cb-c373061]
    at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [bending.jar:git-Spigot-76236cb-c373061]
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [bending.jar:git-Spigot-76236cb-c373061]
    at java.lang.Thread.run(Thread.java:745) [?:1.8.0_60]