[10:54:39] [Craft Scheduler Thread - 1673/WARN]: Exception in thread "Craft Scheduler Thread - 1673"
[10:54:39] [Craft Scheduler Thread - 1673/WARN]: org.apache.commons.lang.UnhandledException: Plugin Autorank v3.8.4 generated an exception while executing task 288
at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at me.armar.plugins.autorank.playtimes.PlaytimesUpdate.updateMinutesPlayed(PlaytimesUpdate.java:39)
at me.armar.plugins.autorank.playtimes.PlaytimesUpdate.updateMinutesPlayed(PlaytimesUpdate.java:85)
at me.armar.plugins.autorank.playtimes.PlaytimesUpdate.run(PlaytimesUpdate.java:30)
at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftTask.run(CraftTask.java:71)
at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
... 3 more

How often do you get this specific error message?

Mhh, sometimes, I think.