Friend keeps getting a Fatal Error

Whenever my friend tries to join our private server he gets a message saying "Fatal Error occurred the connection has been terminated"

We are hosting the Trollcraft modpack and have added our own mods, Buildcraft, Aether and Galacticraft. We know the issue is with galacticraft as whenever we remove the mod my friend can join fine.

This is what he receives in his console (He is using the Twitch Launcher)

 There was a critical exception handling a packet on channel FORGE
java.lang.NullPointerException
at net.minecraftforge.fluids.FluidRegistry.loadFluidDefaults(FluidRegistry.java:117)
at net.minecraftforge.fluids.FluidRegistry.initFluidIDs(FluidRegistry.java:82)
at net.minecraftforge.common.network.FluidIdRegistryMessageHandler.channelRead0(FluidIdRegistryMessageHandler.java:15)
at net.minecraftforge.common.network.FluidIdRegistryMessageHandler.channelRead0(FluidIdRegistryMessageHandler.java:11)
at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:98)
at io.netty.channel.DefaultChannelHandlerContext.invokeChannelRead(DefaultChannelHandlerContext.java:337)
at io.netty.channel.DefaultChannelHandlerContext.fireChannelRead(DefaultChannelHandlerContext.java:323)
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)
at io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:111)
at io.netty.channel.DefaultChannelHandlerContext.invokeChannelRead(DefaultChannelHandlerContext.java:337)
at io.netty.channel.DefaultChannelHandlerContext.fireChannelRead(DefaultChannelHandlerContext.java:323)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:785)
at io.netty.channel.embedded.EmbeddedChannel.writeInbound(EmbeddedChannel.java:169)
at cpw.mods.fml.common.network.internal.FMLProxyPacket.func_148833_a(FMLProxyPacket.java:77)
at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:212)
at net.minecraft.client.multiplayer.GuiConnecting.func_73876_c(SourceFile:78)
at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1661)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:973)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:898)
at net.minecraft.client.main.Main.main(SourceFile:148)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMe
 

I've already tried googling this issue and I haven't found any fixes, and the only way is to just remove galacticraft which is something we don't really want. Does anybody have a fix for this without removing galacticraft? 

Thank you