Have at the moment two problems with my mod:

1. When I try to send a packet this message is being printed: 

[04jun2019 20:34:56.138] [Client thread/WARN] [net.minecraft.client.network.NetHandlerPlayClient/]: Unknown custom packed identifier: feuniversal:fenet

2. The new way to display a GuiContainer get stuck(no errors are being printed) at this line:

BlockPos pos = openCon.getAdditionalData().readBlockPos();

I can print to the console before the line but not after and therefore the GuiConatiner isn't returned.

Yes, but at the moment I have just one registered:

Packet registry:

public class PacketHandlerFE {
	
	private final String PROTOCOL_VERSION = "1";
	private int ID = 0;
	private final SimpleChannel INSTANCE;
	
	public PacketHandlerFE(String channelName) {
		this.INSTANCE = NetworkRegistry.newSimpleChannel(new ResourceLocation("feuniversal", channelName),
			    () -> PROTOCOL_VERSION,
			    PROTOCOL_VERSION::equals,
			    PROTOCOL_VERSION::equals);
	}
	
	public SimpleChannel getSimpleChannel()
	{
		return this.INSTANCE;
	}
	
	public void registerPackets()
	{
		this.INSTANCE.registerMessage(ID++, UpdateTileEntityS.class, UpdateTileEntityS::encode, UpdateTileEntityS::decode, UpdateTileEntityS.Handler::handle);
	}
	
	public <MSG> void sendTo(MSG msg, EntityPlayerMP player)
	{
		if (!(player instanceof FakePlayer))
		{
			this.INSTANCE.sendTo(msg, player.connection.netManager, NetworkDirection.PLAY_TO_CLIENT);
		}
	}
	
	/*public void send(PacketTarget target, Object msg)
	{
		this.INSTANCE.send(target, msg);
	}*/
	
}

and GuiHandler:

public GuiScreen openGui(FMLPlayMessages.OpenContainer openCon)
	{
		
		BlockPos pos = openCon.getAdditionalData().readBlockPos();
		World world = Minecraft.getInstance().world;
		EntityPlayer player = Minecraft.getInstance().player;
		if(guiElement.get(openCon.getId()) != null)
		{
			return new guiElement.get(openCon.getId()).openGuiContainer(player, world, pos);
		}
		else
		{
			player.sendMessage(new TextComponentTranslation("error.opengui.null"));
			return null;
		}
	}

 

I create the PacketHandlerFE in my main mod class.

This where I open it:

@Override
	public boolean onBlockActivated(IBlockState state, World worldIn, BlockPos pos, EntityPlayer player, EnumHand hand,
			EnumFacing side, float hitX, float hitY, float hitZ) {
		if(!player.isSneaking())
		{
			if(!worldIn.isRemote)
			{
				TileEntityProducerBasicDirt tile = (TileEntityProducerBasicDirt) worldIn.getTileEntity(pos);
				NetworkHooks.openGui((EntityPlayerMP) player, new IInteractionObject() {

					@Override
					public ITextComponent getName() {
						return new TextComponentString("");
					}

					@Override
					public boolean hasCustomName() {
						return false;
					}

					@Override
					public ITextComponent getCustomName() {
						return new TextComponentString("");
					}

					@Override
					public Container createContainer(InventoryPlayer playerInventory, EntityPlayer playerIn) {
						return new DirtProducerContainer(playerIn, tile);
					}

					@Override
					public String getGuiID() {
						return FEUniversal.getInstance().dirtProducerID.toString();
					}
					
				});
			}
			else
			{
				return true;
			}
		}
		return super.onBlockActivated(state, worldIn, pos, player, hand, side, hitX, hitY, hitZ);
	}

I can see that "onBlockActivated" is deprecated but I don't what to use instead.

The PacketHandler is just created like this: 

private PacketHandlerFE network = new PacketHandlerFE("fenet");
//The following is using that instance
  public PacketHandlerFE getNetwork()
    {
    	return this.network;
    }

//and

private void doSetup(final FMLCommonSetupEvent event)
    {
    	this.network.registerPackets();
    }

The getNetwork() getter is only being used to send packets.

And thank you for informing me, that I had to write additional GUI data. Could find so much information about the new Gui system.

7 minutes ago, WOTBLITZ said:

The PacketHandler is just created like this:

private PacketHandlerFE network = new PacketHandlerFE("fenet");
//The following is using that instance
  public PacketHandlerFE getNetwork()
    {
    	return this.network;
    }

//and

private void doSetup(final FMLCommonSetupEvent event)
    {
    	this.network.registerPackets();
    }

The getNetwork() getter is only being used to send packets.

And thank you for informing me, that I had to write additional GUI data. Could find so much information about the new Gui system.

Should I register my SimplChannel at FMLCommonSetupEvent instead?

The SimplChannel  is working as the client is being updated.

I haven't changed my code apart from my GuiHandler.  The problem is that this

[04jun2019 20:34:56.138] [Client thread/WARN] [net.minecraft.client.network.NetHandlerPlayClient/]: Unknown custom packed identifier: feuniversal:fenet

is being printed whenever I try to send a packet.

Hmm..., You really must learn how to read. First I said my main mod class then I mentioned a getter which means that I am created it on when my mod object gets init!

However, I tried to change register the channel st FMLCommonSetupEvent, no difference.

Also tried changing how I registered my channel from:

 NetworkRegistry.newSimpleChannel(new ResourceLocation("feuniversal", channelName),
			    () -> PROTOCOL_VERSION,
			    PROTOCOL_VERSION::equals,
			    PROTOCOL_VERSION::equals);

to

NetworkRegistry.ChannelBuilder
				.named(new ResourceLocation("feuniversal", channelName))
				.clientAcceptedVersions(PROTOCOL_VERSION::equals)
				.serverAcceptedVersions(PROTOCOL_VERSION::equals)
				.networkProtocolVersion(() -> PROTOCOL_VERSION)
				.simpleChannel();

and still no difference. And this was taken from two different projects at Github.

I know this topic is a bit old, but I just had the same issue and a Google search points here.

 

If your packet is working correctly, and its just the warning in the log, you've likely made the same mistake as me.

Inside the "messageConsumer" you provided when registering your packet, you need to set the packet handled flag to true. "context.get().setPacketHandled(true);"

 

If it isn't set to true, NetworkHooks.onCustomPayload will return false, and ClientPlayNetHandler.handleCustomPayload will post the warning