Bad packet id 2

[Veryance]

Hi guys, I am running a modified (dunno if it's too heavy to disqualify me for some help ) version of dw20 1.6.4 pack, with a couple of mod updates and 1 addition.
When I connect i receive this error:

Internal exception: java.io.IOException: Bad packet id 2

Here is my log if that's useful, thanks in advance!

Spoiler

---- Minecraft Crash Report ----
// My bad.

Time: 2/12/14 12:46 AM
Description: Exception in world tick

java.lang.RuntimeException: java.lang.NullPointerException
at ic2.core.network.NetworkManagerClient.setField(NetworkManagerClient.java:455)
at ic2.core.network.NetworkManagerClient.processInitPacket(NetworkManagerClient.java:416)
at ic2.core.network.NetworkManagerClient.onPacketData(NetworkManagerClient.java:206)
at cpw.mods.fml.common.network.NetworkRegistry.handlePacket(NetworkRegistry.java:255)
at cpw.mods.fml.common.network.NetworkRegistry.handleCustomPacket(NetworkRegistry.java:245)
at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:85)
at net.minecraft.client.multiplayer.NetClientHandler.func_72501_a(NetClientHandler.java:1651)
at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:61)
at net.minecraft.network.TcpConnection.func_74428_b(TcpConnection.java:462)
at net.minecraft.client.multiplayer.NetClientHandler.func_72551_d(NetClientHandler.java:281)
at net.minecraft.client.multiplayer.WorldClient.func_72835_b(WorldClient.java:99)
at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1930)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:910)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:838)
at net.minecraft.client.main.Main.main(SourceFile:101)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:131)
at net.minecraft.launchwrapper.Launch.main(Launch.java:27)
Caused by: java.lang.NullPointerException
at ic2.core.network.DataEncoder.copyValue(DataEncoder.java:474)
at ic2.core.network.NetworkManagerClient.setField(NetworkManagerClient.java:451)
... 20 more


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
at ic2.core.network.NetworkManagerClient.setField(NetworkManagerClient.java:455)
at ic2.core.network.NetworkManagerClient.processInitPacket(NetworkManagerClient.java:416)
at ic2.core.network.NetworkManagerClient.onPacketData(NetworkManagerClient.java:206)
at cpw.mods.fml.common.network.NetworkRegistry.handlePacket(NetworkRegistry.java:255)
at cpw.mods.fml.common.network.NetworkRegistry.handleCustomPacket(NetworkRegistry.java:245)
at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:85)
at net.minecraft.client.multiplayer.NetClientHandler.func_72501_a(NetClientHandler.java:1651)
at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:61)
at net.minecraft.network.TcpConnection.func_74428_b(TcpConnection.java:462)
at net.minecraft.client.multiplayer.NetClientHandler.func_72551_d(NetClientHandler.java:281)

-- Affected level --
Details:
Level name: MpServer
All players: 1 total; [EntityClientPlayerMP['Veryance'/2510, l='MpServer', x=-992.77, y=68.62, z=-348.52]]
Chunk stats: MultiplayerChunkCache: 441
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (8,64,8), Chunk: (at 8,4,8 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 67690804 game time, 71212207 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false

 

[UniZero]

What mods did you update? If one of them was IC2 then either force update the pack or take IC2 from another pack. if you force update it will wipe all your additional mods and any config changes you made.

 

[Veryance]

I did not update ic2. I updated calclavia core, mffs, universal energy core, and added atomic science.

 

[UniZero]

Did you add / update the mods all at once? If so, then do it one at a time with the base pack to figure out the problem.