[23:03:07] [Craft Scheduler Thread - 2455/WARN]: [MobHunting] Plugin MobHunting v5.6.1 generated an exception while executing task 1241401
java.util.ConcurrentModificationException: null
at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429) ~[?:1.8.0_72]
at java.util.HashMap$EntryIterator.next(HashMap.java:1463) ~[?:1.8.0_72]
at java.util.HashMap$EntryIterator.next(HashMap.java:1461) ~[?:1.8.0_72]
at one.lindegaard.MobHunting.Messages$1.run(Messages.java:514) ~[?:?]
at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:58) ~[patched_1.12.2.jar:git-Paper-1375]
at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:52) [patched_1.12.2.jar:git-Paper-1375]
at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22) [patched_1.12.2.jar:git-Paper-1375]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_72]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_72]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_72]

Please test newest build on my jenkins server.

Is it fixed?

Yep thanks. :)

Thank you, then I will make a release today :-)