Unexpected Multiplayer Disconnection

[MoYuan-CN]

Description

Client crashes when navigation between velocity-based sub-servers with Plasmo Voice.
The crash happens during packet handling (minecraft:custom_payload), resulting in a NullPointerException inside the voice client networking handler.

Disconnection Report

disconnect-2026-03-20_23.02.55-client.txt

Environment

• Minecraft: 1.21.11
• Loader: Fabric 0.18.4
• Fabric API: 0.141.3
• Plasmo Voice: 2.1.8
• Java: 21 (Microsoft OpenJDK)
• OS: Windows 10

Reproducibility

Sometimes

[apehum]

Thanks for the report!

Most likely happens when someone starts to speak in the group/broadcast when switching servers.
Not sure if there's a way to fix it proxy-side, but I made a quick-fix client-side that should work: https://github.com/plasmoapp/plasmo-voice/releases/tag/2.1.9-SNAPSHOT.

[MoYuan-CN]

Hi, I tried to use 2.1.9-SNAPSHOT on client-side, and it works perfectly!
At least now my players do not disconnect to my server that frequently.

[Postman67]

UPDATE: FIXED by increasing velocity.max-plugin-message-payload-size

I'm getting this issue, even after updating all versions to the SNAPSPOT linked here. Use Velocity, trying to connect, no dice. Before it would give me network protocol error, and I was able to try again and it worked, now it just hangs at "Connecting" with nothing in the client or server logs.

Log below is with servers running SNAPSPOT, and client running stable.

disconnect-2026-04-06_21.56.47-client.txt

The only "log" I got client-side running SNAPSPOT is below

[21:37:11] [Render thread/ERROR]:
Encountered exception while handling in channel with name "plasmo:voice/v2"
java.lang.NullPointerException: Cannot invoke "net.minecraft.class_634.method_48296()" because the return value of "net.minecraft.class_310.method_1562()" is null
at knot//su.plo.voice.client.connection.ModClientChannelHandler.receive(ModClientChannelHandler.java:85)
at knot//su.plo.voice.client.connection.ModClientChannelHandler.receive(ModClientChannelHandler.java:47)
at knot//net.fabricmc.fabric.impl.networking.client.ClientPlayNetworkAddon.receive(ClientPlayNetworkAddon.java:77)
at knot//net.fabricmc.fabric.impl.networking.client.ClientPlayNetworkAddon.receive(ClientPlayNetworkAddon.java:39)
at knot//net.fabricmc.fabric.impl.networking.AbstractChanneledNetworkAddon.handle(AbstractChanneledNetworkAddon.java:102)
at knot//net.minecraft.class_8673.handler$bcl000$fabric-networking-api-v1$onCustomPayload(class_8673.java:1050)
at knot//net.minecraft.class_8673.method_52780(class_8673.java)
at knot//net.minecraft.class_2658.method_53024(class_2658.java:49)
at knot//net.minecraft.class_2658.method_65081(class_2658.java:19)
at knot//net.minecraft.class_11980$class_11981.method_74450(class_11980.java:55)
at knot//net.minecraft.class_11980.method_74449(class_11980.java:38)
at knot//net.minecraft.class_310.method_1523(class_310.java:1337)
at knot//net.minecraft.class_310.method_1514(class_310.java:966)
at knot//net.minecraft.client.main.Main.main(Main.java:250)
at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:514)
at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:72)
at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(Unknown Source)
at java.base/java.lang.reflect.Method.invoke(Unknown Source)
at com.modrinth.theseus.MinecraftLaunch.relaunch(MinecraftLaunch.java:63)
at com.modrinth.theseus.MinecraftLaunch.main(MinecraftLaunch.java:28)

My flow is:
Fabric 1.21.11 client -> Velocity -> 1.20.1 HUB with ViaVersion & Latest Plasmo -> Fabric 1.21.11 server with Latest Plasmo

Using forced host on Velocity side straight to the Fabric server gives me

exception encountered in com.velocitypowered.proxy.connection.backend.BackendPlaySessionHandler@2012c6b4
com.velocitypowered.proxy.util.except.QuietRuntimeException: A packet did not decode successfully (invalid data). For more information, launch Velocity with -Dvelocity.packet-decode-logging=true to see more.

Further error digging gives me this:

message.txt