CRAFTBOOK-2771 - Reported by RobinTR

21:41:41 [severe] java.lang.NullPointerException
21:41:41 [severe] Exception in thread "Thread-21"
21:41:41 [severe] at com.sk89q.craftbook.bukkit.Updater.versionCheck(Updater.java:422)
21:41:41 [severe] at com.sk89q.craftbook.bukkit.Updater.access$400(Updater.java:45)
21:41:41 [severe] at com.sk89q.craftbook.bukkit.Updater$UpdateRunnable.run(Updater.java:503)
21:41:41 [severe] at java.lang.Thread.run(Unknown Source)

Comment by me4502

That's a connection error, it has been hidden in the latest dev builds. You can disable the automatic updater to stop recieving the error, but the error is harmless.