We just updated to 5.1.1 from the old 4.0 version. Everything seems to work fine, all the commands work and etc. Except for tempban, which throws this error:

[09:52:51] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'tempban' in plugin BanManager v5.1.1
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[start.jar:git-Spigot-529ff99-2acb9e4]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) ~[start.jar:git-Spigot-529ff99-2acb9e4]
at org.bukkit.craftbukkit.v1_8_R2.CraftServer.dispatchCommand(CraftServer.java:646) ~[start.jar:git-Spigot-529ff99-2acb9e4]
at net.minecraft.server.v1_8_R2.PlayerConnection.handleCommand(PlayerConnection.java:1133) [start.jar:git-Spigot-529ff99-2acb9e4]
at net.minecraft.server.v1_8_R2.PlayerConnection.a(PlayerConnection.java:968) [start.jar:git-Spigot-529ff99-2acb9e4]
at net.minecraft.server.v1_8_R2.PacketPlayInChat.a(PacketPlayInChat.java:45) [start.jar:git-Spigot-529ff99-2acb9e4]
at net.minecraft.server.v1_8_R2.PacketPlayInChat.a(PacketPlayInChat.java:1) [start.jar:git-Spigot-529ff99-2acb9e4]
at net.minecraft.server.v1_8_R2.PlayerConnectionUtils$1.run(SourceFile:13) [start.jar:git-Spigot-529ff99-2acb9e4]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_25]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_25]
at net.minecraft.server.v1_8_R2.SystemUtils.a(SourceFile:60) [start.jar:git-Spigot-529ff99-2acb9e4]
at net.minecraft.server.v1_8_R2.MinecraftServer.A(MinecraftServer.java:710) [start.jar:git-Spigot-529ff99-2acb9e4]
at net.minecraft.server.v1_8_R2.DedicatedServer.A(DedicatedServer.java:368) [start.jar:git-Spigot-529ff99-2acb9e4]
at net.minecraft.server.v1_8_R2.MinecraftServer.z(MinecraftServer.java:651) [start.jar:git-Spigot-529ff99-2acb9e4]
at net.minecraft.server.v1_8_R2.MinecraftServer.run(MinecraftServer.java:554) [start.jar:git-Spigot-529ff99-2acb9e4]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_25]
Caused by: java.lang.NullPointerException
at me.confuser.banmanager.configs.TimeLimitsConfig.isPastLimit(TimeLimitsConfig.java:48) ~[?:?]
at me.confuser.banmanager.commands.TempBanCommand.onCommand(TempBanCommand.java:82) ~[?:?]
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[start.jar:git-Spigot-529ff99-2acb9e4]
... 15 more

The oddest part is that it only throws this error to people who have the tempban permission node, if they dont have it it says "no permission" as it should. But if you're opped the tempban command works just fine.