--- ../src-base/minecraft/cpw/mods/fml/common/network/internal/HandshakeCompletionHandler.java
+++ ../src-work/minecraft/cpw/mods/fml/common/network/internal/HandshakeCompletionHandler.java
@@ -13,9 +13,15 @@
     @Override
     protected void channelRead0(ChannelHandlerContext ctx, CompleteHandshake msg) throws Exception
     {
+        // Cauldron start - attempt to fix race condition with attr being null
+        Object attr = ctx.channel().attr(NetworkDispatcher.FML_DISPATCHER);
+        if (attr != null)
+        {
         NetworkDispatcher dispatcher = ctx.channel().attr(NetworkDispatcher.FML_DISPATCHER).getAndRemove();
         dispatcher.completeHandshake(msg.target);
     }
+        // Cauldron end
+    }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception