Hello :)

On my server, I can interract (build cart, change direction in cargo manager, change drill intelligence) normaly with Steve cart but some other player can (but it work normally on local for everyone). They get kicked by the server but no server crash. I have the following message on the server
[Netty Epoll Server IO #7/ERROR] [FML]: There was a critical exception handling a packet on channel rebornCore io.netty.handler.codec.DecoderException: java.lang.NullPointerException: Undefined message for discriminator 5 in channel rebornCore at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:98) ~[minecraft_server.1.12.2.jar:?] at io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:111) ~[minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) ~[minecraft_server.1.12.2.jar:?] at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1334) ~[minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[minecraft_server.1.12.2.jar:?] at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:926) ~[minecraft_server.1.12.2.jar:?] at io.netty.channel.embedded.EmbeddedChannel.writeInbound(EmbeddedChannel.java:274) ~[minecraft_server.1.12.2.jar:?] at net.minecraftforge.fml.common.network.internal.FMLProxyPacket.func_148833_a(FMLProxyPacket.java:99) [FMLProxyPacket.class:?] at net.minecraft.network.NetworkManager.channelRead0(NetworkManager.java:147) [gw.class:?] at net.minecraft.network.NetworkManager.channelRead0(NetworkManager.java:49) [gw.class:?] at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [minecraft_server.1.12.2.jar:?] at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.handleServerSideCustomPacket(NetworkDispatcher.java:443) [NetworkDispatcher.class:?] at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.channelRead0(NetworkDispatcher.java:265) [NetworkDispatcher.class:?] at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.channelRead0(NetworkDispatcher.java:72) [NetworkDispatcher.class:?] at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [minecraft_server.1.12.2.jar:?] at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:293) [minecraft_server.1.12.2.jar:?] at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:267) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [minecraft_server.1.12.2.jar:?] at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:293) [minecraft_server.1.12.2.jar:?] at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:267) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [minecraft_server.1.12.2.jar:?] at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:293) [minecraft_server.1.12.2.jar:?] at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:267) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [minecraft_server.1.12.2.jar:?] at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [minecraft_server.1.12.2.jar:?] at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:287) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [minecraft_server.1.12.2.jar:?] at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1334) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [minecraft_server.1.12.2.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [minecraft_server.1.12.2.jar:?] at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:926) [minecraft_server.1.12.2.jar:?] at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:1017) [minecraft_server.1.12.2.jar:?] at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:394) [minecraft_server.1.12.2.jar:?] at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:299) [minecraft_server.1.12.2.jar:?] at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858) [minecraft_server.1.12.2.jar:?] at java.lang.Thread.run(Thread.java:745) [?:1.8.0_45-internal] Caused by: java.lang.NullPointerException: Undefined message for discriminator 5 in channel rebornCore at net.minecraftforge.fml.common.network.FMLIndexedMessageToMessageCodec.decode(FMLIndexedMessageToMessageCodec.java:99) ~[FMLIndexedMessageToMessageCodec.class:?] at net.minecraftforge.fml.common.network.FMLIndexedMessageToMessageCodec.decode(FMLIndexedMessageToMessageCodec.java:40) ~[FMLIndexedMessageToMessageCodec.class:?] at io.netty.handler.codec.MessageToMessageCodec$2.decode(MessageToMessageCodec.java:81) ~[minecraft_serve r.1.12.2.jar:?] at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:88) ~[minecraft_server.1.12.2.jar:?]

Feel free to ask for more informations

Keep up the good work, we love the mod and the port !

Update reborn core, reopen if still an issue.