It have always works fine, but now this error:

00:50:58 [SEVERE] Exception in thread "Thread-53"
00:50:58 [SEVERE] java.lang.NullPointerException
00:50:58 [SEVERE] at net.milkbowl.vault.permission.plugins.Permission_PermissionsEx.playerInGroup(Permission_PermissionsEx.java:74)
00:50:58 [SEVERE] at me.Wouter0100.NLMinecraftPlugin.NLMinecraftPluginSocketListener.onClientRecieve(NLMinecraftPluginSocketListener.java:66)
00:50:58 [SEVERE] at de.kumpelblase2.transmit.TransmitServer.fireClientRecieveEvent(TransmitServer.java:235)
00:50:58 [SEVERE] at de.kumpelblase2.transmit.TransmitServer.handle(TransmitServer.java:191)
00:50:58 [SEVERE] at de.kumpelblase2.transmit.ClientConnectionThread.run(ClientConnectionThread.java:128)
00:50:58 [SEVERE] at java.lang.Thread.run(Thread.java:636)

I think its Vault because before 1.2.3 it works fine.

Thanks,
Wouter0100

I'm not running it in a Thread, (I think so) and i need to update PEX?

this isn't a Vault issue, this is a PEX issue (or a plugin issue). Also these methods aren't thread-safe. you're likely to break something if you run them in a thread.

00:50:58 [SEVERE] Exception in thread "Thread-53" <- doesn't really happen if the operation is being handled on a thread other than the server-thread. there's also a lot of extra stuff going on that I'd suggest contacting the original plugin author about (unless that's you).

Overall, yes I'd check with PEX about this.