disconnected with: IllegalStateException : Adding 1 elements would exceed capacity of 128 @ com.google.common.base.Preconditions:593

[dementisimus]

comment: only one player gets kicked. Other players remain on the server.

java.lang.IllegalStateException: Adding 1 elements would exceed capacity of 128 at com.google.common.base.Preconditions.checkState(Preconditions.java:593) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at net.md_5.bungee.util.BoundedArrayList.checkSize(BoundedArrayList.java:19) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at net.md_5.bungee.util.BoundedArrayList.add(BoundedArrayList.java:25) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at net.md_5.bungee.connection.UpstreamBridge.handle(UpstreamBridge.java:269) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at net.md_5.bungee.protocol.packet.PluginMessage.handle(PluginMessage.java:102) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at net.md_5.bungee.netty.HandlerBoss.channelRead(HandlerBoss.java:105) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:296) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:714) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:650) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:576) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[waterfall.jar:git:Waterfall-Bootstrap:1.16-R0.2-SNAPSHOT:9234e50:358] at java.lang.Thread.run(Thread.java:832) [?:?]

[Janmm14]

Very likely malicious player.

[Brokkonaut]

No it is some bug in here:
https://github.com/SpigotMC/BungeeCord/blob/master/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java#L251
All (not cancelled) minecraft:register or minecraft:brand messages from the client to the bungee since the client connected are stored in a list and sent to the new server after a server switch.

The problem is that those messages are never removed from that list and after every server switch the client resends the minecraft:register and minecraft:brand packets. So they stack up and at some time will reach the limit of 128 and kick the player. We can see this very often since 1.16 on our server, i got kicked some times too.

I would recommend not to store them in that list at all (at least for 1.16 clients), because the client will resend them anyways. so there is no need to store them (maybe it was different in a previous version, i did not test that)

[Leymooo]

Client only resends minecraft:brand or MC|Brand when recieves Login(JoinGame) packet. Maybe forge or fabric resend register stuff but not vanilla

[Brokkonaut]

I created a plugin that logs those messages for debugging. The vanilla client definitely sends a minecraft:brand on server switch. Forge/Fabric clients also send one or more minecraft:register packets on server switch.

Vanilla Client:

[playername|/x.x.x.x:50282] <-> ServerConnector [Farmen] has connected
Setting stored Location for playername: Farmen
[/x.x.x.x:50282|playername] <-> DownstreamBridge <-> [Freebuild] has disconnected
[BungeePluginMessages]: Message to playername: minecraft:register - [bungeecord:main, worldedit:cui, vanishnopacket:status]
[BungeePluginMessages]: Message to playername: minecraft:brand - Paper
[BungeePluginMessages]: Message from playername: minecraft:brand - vanilla

Fabric client, VoxelMap, WorldEditCUI:

[playername|/x.x.x.x:58999] <-> ServerConnector [Freebuild] has connected
Setting stored Location for playername: Freebuild
[/x.x.x.x:58999|playername] <-> DownstreamBridge <-> [Creative] has disconnected
[BungeePluginMessages]: Message to playername: minecraft:register - [bungeecord:main, worldedit:cui, vanishnopacket:status]
[BungeePluginMessages]: Message to playername: minecraft:brand - Paper
[BungeePluginMessages]: Message from playername: minecraft:brand - fabric
[BungeePluginMessages]: Message from playername: minecraft:register - [fabric:container/open, fabric-screen-handler-api-v1:open_screen, fabric:registry/sync, worldedit:cui]
[BungeePluginMessages]: Message from playername: minecraft:register - [worldinfo:world_id]

Plugin event handler code:

@EventHandler
public void onPluginMessage(PluginMessageEvent e) {
    if (e.getSender() instanceof ProxiedPlayer) {
        getLogger().info("Message from " + ((ProxiedPlayer) e.getSender()).getName() + ": " + e.getTag() + " - " + decode(e.getTag(), e.getData()));
    } else if (e.getReceiver() instanceof ProxiedPlayer) {
        getLogger().info("Message to " + ((ProxiedPlayer) e.getReceiver()).getName() + ": " + e.getTag() + " - " + decode(e.getTag(), e.getData()));
    }
}

private String decode(String tag, byte[] data) {
    if (tag.equals("minecraft:register") || tag.equals("minecraft:unregister")) {
        return Arrays.toString(new String(data, com.google.common.base.Charsets.UTF_8).split("\0"));
    }
    return new String(data, com.google.common.base.Charsets.UTF_8);
}

[Janmm14]

I highly recommend to create an issue on BungeeCord for this in that case.

[dementisimus]

I always use the latest MC-Version. In this case it was MC 1.16.1 - Vanilla, no modified Client or so

[TNTUP]

I've seen that error when someone logs in with Geyser MC (Bedrock Edition to Java Edition proxy)

[ikuria]

I created a plugin that logs those messages for debugging. The vanilla client definitely sends a minecraft:brand on server switch. Forge/Fabric clients also send one or more minecraft:register packets on server switch.

Vanilla Client:

[playername|/x.x.x.x:50282] <-> ServerConnector [Farmen] has connected
Setting stored Location for playername: Farmen
[/x.x.x.x:50282|playername] <-> DownstreamBridge <-> [Freebuild] has disconnected
[BungeePluginMessages]: Message to playername: minecraft:register - [bungeecord:main, worldedit:cui, vanishnopacket:status]
[BungeePluginMessages]: Message to playername: minecraft:brand - Paper
[BungeePluginMessages]: Message from playername: minecraft:brand - vanilla

Fabric client, VoxelMap, WorldEditCUI:

[playername|/x.x.x.x:58999] <-> ServerConnector [Freebuild] has connected
Setting stored Location for playername: Freebuild
[/x.x.x.x:58999|playername] <-> DownstreamBridge <-> [Creative] has disconnected
[BungeePluginMessages]: Message to playername: minecraft:register - [bungeecord:main, worldedit:cui, vanishnopacket:status]
[BungeePluginMessages]: Message to playername: minecraft:brand - Paper
[BungeePluginMessages]: Message from playername: minecraft:brand - fabric
[BungeePluginMessages]: Message from playername: minecraft:register - [fabric:container/open, fabric-screen-handler-api-v1:open_screen, fabric:registry/sync, worldedit:cui]
[BungeePluginMessages]: Message from playername: minecraft:register - [worldinfo:world_id]

Plugin event handler code:

@EventHandler
public void onPluginMessage(PluginMessageEvent e) {
    if (e.getSender() instanceof ProxiedPlayer) {
        getLogger().info("Message from " + ((ProxiedPlayer) e.getSender()).getName() + ": " + e.getTag() + " - " + decode(e.getTag(), e.getData()));
    } else if (e.getReceiver() instanceof ProxiedPlayer) {
        getLogger().info("Message to " + ((ProxiedPlayer) e.getReceiver()).getName() + ": " + e.getTag() + " - " + decode(e.getTag(), e.getData()));
    }
}

private String decode(String tag, byte[] data) {
    if (tag.equals("minecraft:register") || tag.equals("minecraft:unregister")) {
        return Arrays.toString(new String(data, com.google.common.base.Charsets.UTF_8).split("\0"));
    }
    return new String(data, com.google.common.base.Charsets.UTF_8);
}

need that plugin, because my server is doing same kicks with same error
waterfall 3.8.1

[ikuria]

still getting this error

[Janmm14]

Suggesting that the error should print out the registered channels.

[spamvictus]

I get this error too, but it seems like no one else has since there weren't any new new comments for months.
Well I would like to look into it codewise. If anybody of you guys reading this has some insights for me to find the bad boy in the code a bit easier... Please spill the beans for me :D

[Janmm14]

@spamvictus there's already a PR linked