LAN crash

[Client thread/FATAL]: Reported exception thrown!
net.minecraft.util.ReportedException: Ticking screen
	at net.minecraft.client.Minecraft.runTick(Minecraft.java:1765) ~[Minecraft.class:?]
	at net.minecraft.client.Minecraft.runGameLoop(Minecraft.java:1038) ~[Minecraft.class:?]
	at net.minecraft.client.Minecraft.run(Minecraft.java:961) [Minecraft.class:?]
	at net.minecraft.client.main.Main.main(Main.java:164) [Main.class:?]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0_51]
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.7.0_51]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.7.0_51]
	at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.7.0_51]
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:134) [launchwrapper-1.9.jar:?]
	at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.9.jar:?]
Caused by: java.lang.NullPointerException
	at com.mojang.util.UUIDTypeAdapter.fromUUID(UUIDTypeAdapter.java:22) ~[UUIDTypeAdapter.class:?]
	at com.mojang.util.UUIDTypeAdapter.write(UUIDTypeAdapter.java:13) ~[UUIDTypeAdapter.class:?]
	at com.mojang.util.UUIDTypeAdapter.write(UUIDTypeAdapter.java:10) ~[UUIDTypeAdapter.class:?]
	at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68) ~[TypeAdapterRuntimeTypeWrapper.class:?]
	at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:89) ~[ReflectiveTypeAdapterFactory$1.class:?]
	at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:195) ~[ReflectiveTypeAdapterFactory$Adapter.class:?]
	at com.google.gson.Gson.toJson(Gson.java:593) ~[Gson.class:?]
	at com.google.gson.Gson.toJson(Gson.java:572) ~[Gson.class:?]
	at com.google.gson.Gson.toJson(Gson.java:527) ~[Gson.class:?]
	at com.google.gson.Gson.toJson(Gson.java:507) ~[Gson.class:?]
	at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:54) ~[YggdrasilAuthenticationService.class:?]
	at com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService.joinServer(YggdrasilMinecraftSessionService.java:61) ~[YggdrasilMinecraftSessionService.class:?]
	at net.minecraft.client.network.NetHandlerLoginClient.handleEncryptionRequest(NetHandlerLoginClient.java:62) ~[NetHandlerLoginClient.class:?]
	at net.minecraft.network.login.server.S01PacketEncryptionRequest.processPacket(S01PacketEncryptionRequest.java:54) ~[S01PacketEncryptionRequest.class:?]
	at net.minecraft.network.login.server.S01PacketEncryptionRequest.processPacket(S01PacketEncryptionRequest.java:62) ~[S01PacketEncryptionRequest.class:?]
	at net.minecraft.network.NetworkManager.processReceivedPackets(NetworkManager.java:247) ~[NetworkManager.class:?]
	at net.minecraft.client.multiplayer.GuiConnecting.updateScreen(GuiConnecting.java:116) ~[GuiConnecting.class:?]
	at net.minecraft.client.Minecraft.runTick(Minecraft.java:1751) ~[Minecraft.class:?]
	... 9 more