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Disconnect Packet Fix

Disconnect Packet Fix

MOD
Works around the MC-271325 bug on Fabric and NeoForge servers (fixes "error sending packet clientbound/minecraft:disconnect")
by ascpixi
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5,969,798 downloads
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Updated Oct 14, 2026
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Bug Fixes Performance Server Utility Utility & QoL
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A mod for Fabric and NeoForge-based Minecraft servers that works around the MC-271325 bug. This bug frequently causes the console to be spammed with exception stacktraces, e.g.:

[22:35:52] [Netty Epoll Server IO #5/ERROR]: Error sending packet clientbound/minecraft:disconnect
io.netty.handler.codec.EncoderException: Sending unknown packet 'clientbound/minecraft:disconnect'
    at MC/net.minecraft.network.handler.PacketCodecDispatcher.encode(PacketCodecDispatcher.java:47) ~[server-intermediary.jar:?]
    at MC/net.minecraft.network.handler.PacketCodecDispatcher.encode(PacketCodecDispatcher.java:14) ~[server-intermediary.jar:?]
    at MC/net.minecraft.network.handler.EncoderHandler.encode(EncoderHandler.java:26) ~[server-intermediary.jar:?]
    at MC/net.minecraft.network.handler.EncoderHandler.encode(EncoderHandler.java:12) ~[server-intermediary.jar:?]
    at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:107) ~[netty-codec-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:881) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:863) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:968) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:856) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.ChannelOutboundHandlerAdapter.write(ChannelOutboundHandlerAdapter.java:113) ~[netty-transport-4.1.97.Final.jar:?]
    at MC/net.minecraft.network.ClientConnection$2.write(ClientConnection.java:530) ~[server-intermediary.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:881) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:940) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:966) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:934) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:984) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1025) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:306) ~[netty-transport-4.1.97.Final.jar:?]
    at MC/net.minecraft.network.ClientConnection.sendInternal(ClientConnection.java:350) ~[server-intermediary.jar:?]
    at MC/net.minecraft.network.ClientConnection.sendImmediately(ClientConnection.java:343) ~[server-intermediary.jar:?]
    at MC/net.minecraft.network.ClientConnection.send(ClientConnection.java:325) ~[server-intermediary.jar:?]
    at MC/net.minecraft.network.ClientConnection.send(ClientConnection.java:319) ~[server-intermediary.jar:?]
    at MC/net.minecraft.network.ClientConnection.exceptionCaught(ClientConnection.java:170) ~[server-intermediary.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:346) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:325) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:317) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.DefaultChannelPipeline$HeadContext.exceptionCaught(DefaultChannelPipeline.java:1377) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:346) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:325) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.DefaultChannelPipeline.fireExceptionCaught(DefaultChannelPipeline.java:907) ~[netty-transport-4.1.97.Final.jar:?]
    at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.handleReadException(AbstractEpollStreamChannel.java:728) ~[netty-transport-classes-epoll-4.1.97.Final.jar:?]
    at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:826) ~[netty-transport-classes-epoll-4.1.97.Final.jar:?]
    at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:509) ~[netty-transport-classes-epoll-4.1.97.Final.jar:?]
    at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:407) ~[netty-transport-classes-epoll-4.1.97.Final.jar:?]
    at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.97.Final.jar:?]
    at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.97.Final.jar:?]
    at java.base/java.lang.Thread.run(Thread.java:1583) [?:?]

This mod serves to fix that until Mojang fixes this bug. The mod itself is extremely minimal, only using a single mixin to inject code to one method.

Disconnect Packet Fix 2.3.0 for NeoForge
MC NeoForge, Server, 26.3
Release 2026-09-18 Get
Disconnect Packet Fix 2.3.0 for Fabric
MC Fabric, Server, 26.3
Release 2026-09-18 Get
Disconnect Packet Fix 2.2.0 for NeoForge
MC NeoForge, Server, 26.2
Release 2026-07-05 Get
Disconnect Packet Fix 2.2.0 for Fabric
MC Fabric, Server, 26.2
Release 2026-07-05 Get
Disconnect Packet Fix 2.1.1 for NeoForge
MC NeoForge, Server, 26.1, 26.1.1, 26.1.2
Release 2026-05-31 Get
Disconnect Packet Fix 2.1.0 for NeoForge
MC NeoForge, Server, 26.1
Release 2026-03-30 Get
Disconnect Packet Fix 2.1.0 for Fabric
MC Fabric, Server, 26.1, 26.1.1, 26.1.2
Release 2026-03-30 Get
Disconnect Packet Fix 2.0.0 for Fabric
MC 1.21.2-Snapshot, 1.21, 1.21.6-snapshot, 1.21.1-Snapshot, Fabric, 1.21.8, 1.21.5, 1.21.4, 1.21.5-Snapshot, 1.21.1, 1.21.6, 1.21.3, 1.21.7, 1.21-Snapshot, Server, 1.21.4-Snapshot
Release 2025-01-07 Get
Disconnect Packet Fix 2.0.1 for NeoForge
MC 1.21.2-Snapshot, 1.21, 1.21.6-snapshot, 1.21.1-Snapshot, 1.21.8, 1.21.5, 1.21.4, 1.21.5-Snapshot, 1.21.1, 1.21.6, 1.21.3, 1.21.7, 1.21-Snapshot, NeoForge, Server, 1.21.4-Snapshot
Release 2025-01-07 Get

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