Could not translate packet ClientboundUpdateTagsPacket

[fresh holly]

Hello.

After updating NullCordX to the new core with 26.1 support on March 27, 2026, players started having serious issues on March 28, 2026.

Current setup:

NullCordX build with 26.1 support
latest versions of Geyser and Floodgate
proxy: BungeeCord
backend: vanilla server 1.21.11 (I can provide exact versions if needed)
Problems:

players using Geyser/Floodgate are getting errors like:
java.lang.NullPointerException: Cannot read the array length because the return value of "java.util.Map.get(Object)" is null
at org.geysermc.geyser.session.cache.TagCache.loadPacket(TagCache.java:97)
at org.geysermc.geyser.translator.protocol.java.JavaUpdateTagsTranslator.translate(JavaUpdateTagsTranslator.java:38)
logs also show:
[Geyser-BungeeCord]: Could not translate packet ClientboundUpdateTagsPacket
in addition, on the backend vanilla server, players’ clients start crashing after about 30 seconds to 3 minutes of gameplay(only bedrok player, java all good)
this has already happened to at least 6 players
These issues were not happening before updating to the new NullCordX 26.1 core.

Could you please tell me:

Is this a known issue with the new NullCordX version?
Could this be related to packet/tag handling with Geyser?
Is there any recommended fix or setting change?
Should I temporarily roll back to the previous stable NullCordX version?

[old musk]

Found errors in the log!

See below for details and possible fixes

java.lang.NullPointerException: Cannot read the array length because the return value of "java.util.Map.get(Object)" is null

Unknown fix!
Class: TagCache
Method: loadPacket
Line: 97
Link: TagCache.java#L97

[fresh holly]

Thanks. I understand the bot detected the error, but it says "Unknown fix".

Could someone please confirm whether NullCordX 26.1 is currently compatible with the latest Geyser/Floodgate in this setup?

My setup:

• proxy: Bungeecord
• backend: Leaf 1.21.11
• latest Geyser and Floodgate
• NullCordX core with 26.1 support

Important details:

• players can join normally
• some players play without any issues
• some other players get client crashes after around 30 seconds to 3 minutes
• this has already happened to at least 6 players
• this started only after updating NullCordX

Would you recommend:

1. changing any NullCordX/Geyser-related settings
2. disabling any packet/tag-related features
3. temporarily rolling back NullCordX to the previous stable version

If needed, I can provide full proxy logs, backend logs, and client crash reports from affected players.
https://dump.geysermc.org/vhMTusV90xGpwnwj0n8dXXc7fEuQd7KA

[old musk]

<:geyser:723981877773598771> Geyser Bungeecord

Possible problems:

• advanced.bedrock.use-haproxy-protocol should ONLY be enabled if you run a reverse UDP proxy in front of Geyser that supports HAPROXY protocol.
• advanced.java.use-haproxy-protocol should ONLY be enabled if either of these apply:
      1. Your server supports HAPROXY protocol (this has nothing to do with if you're using BungeeCord or Velocity).
      2. You have the exact same option enabled in your BungeeCord/Velocity config (it is off by default).

Git info

Up to date: Yes
Commit: cc7ae04
Branch: master

Listen address

0.0.0.0:19132 (internal IP)

Remote address

Direct connection

Auth type

FLOODGATE

Server platform

NullCordX 26.1-R0.1-SNAPSHOT

Mar 28, 2026, 5:12 PM

[fresh holly]

I do use HAProxy / Proxy Protocol through NeoProtect.

So in my case this warning may be relevant.
My setup is:

• NeoProtect in front of the proxy
• NullCordX/Bungeecord
• Geyser + Floodgate
• backend: Leaf 1.21.11

Could you please confirm which settings should be enabled in this exact setup?

From the Geyser bot output, it looks like Geyser is using direct connection mode.
So should I only enable:

• advanced.bedrock.use-haproxy-protocol = true
  and keep checking NullCordX/Velocity haproxy-protocol settings?

Also, could NullCordX 26.1 have changed Proxy Protocol handling for Geyser/Floodgate?
The issue started only after updating NullCordX.

Additional details:

The error appears in the NullCordX server console.

Connection flow is:

• players join the authentication server first (1.16.5), and they are not kicked there
• then they move to the lobby server (1.16.5)
• then they are sent to the vanilla server running Leaf 1.21.11

The main issue happens on the final vanilla Leaf 1.21.11 server:

• some players get kicked or their client crashes completely after around 5 to 30 seconds, sometimes after about 1 minute
• other players can play normally without any issues

Players reported this on versions:

• 1.21.132
• 1.21.1
• 1.21.3

[dense jewel]

NullCordX is not supported, does this also occur on Velocity or BungeeCord?

[fresh holly]

I haven't checked! That's weird, it's just a fork of BungeeCord. Damn, that's a shame!

[balmy valve]

Just use Velocity

[fresh holly]

velocity 26.1 support? or better 1.21.11 for now?

[dense jewel]

velocity supports 26.1, yes

[fresh holly]

https://github.com/GeyserMC/Geyser/issues/6261
Players are experiencing this error in regular Velocity too! And before the recent update, even NullcordX (fork bungeecord) didn't have this error.

[fresh holly]

hm?

[formal mist]

try and to use velocity with bungeeguard