1.12.2 Connection closes when moving inventory item on 1.21.5 server

[brebathe]

'/viaversion dump' Output

https://dump.viaversion.com/3b5fd2344d2b8b667791d7e8d1487c704c8f89806c175c56d4478f8c99466ee9

Server/Client Error

[13:59:16 INFO]: [connected player] Brebalt (/REDACTED) has disconnected: An internal error occurred in your connection.
[13:59:16 ERROR]: [connected player] Brebalt (/REDACTED): exception encountered in com.velocitypowered.proxy.connection.client.ClientPlaySessionHandler@2980f00c
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.
[13:59:16 INFO]: [server connection] Brebalt -> survival has disconnected
[13:59:16 INFO] [simpleproxychat]: Brebalt has left the network. (survival)

Bug Description

Moving items on 1.12.2 causes error in connection, when connecting to 1.21.5 Purpur server.

Steps to Reproduce

1. Login with 1.12.2
2. Go to survival ( 1.21.5, Purpur )
3. Try to move items in inventory
4. Disconnects with error "An unexpected error occured in your connection"

Additional Server Info

No response

Checklist

• Via plugins are only running on EITHER the backend servers (e.g. Paper) OR the proxy (e.g. Velocity), not on both.
• I have included a ViaVersion dump.
• If applicable, I have included a paste (not a screenshot) of the error.
• I have tried a build from https://ci.viaversion.com/ and the issue still persists.

[Barvalg]

Please update all Via* plugins from https://ci.viaversion.com/ .In case the issue still persists send the new dump and the issue will be reopened

Athena Log Analysis

Platform Information:

Property	Details
Contains Via	❌
Platform Type	Velocity
Is Proxy	✅

[kennytv]

Try moving Via plugins to the backend, you have lots of stuff on the proxy that often interferes with it

[brebathe]

Can I put it on both?

[brebathe]

what interferes with it? I might be able to solve it by removing some plugins on the proxy

[kennytv]

Limbo, also sometimes protocolize

[brebathe]

Ill try removing protocolize, as it only offers 2fa for librelogin but 2fa doesnt work.

[brebathe]

I ended up fixing it by removing protocolize, thanks for the help!

[brebathe]

But items are finiky, dropping items doesnt always register on the client side. Could I install ViaVersion on both the proxy and backends?

[kennytv]

It only works properly if installed on only either one, not both

[brebathe]

I moved them to the backends but the items and signs barely work, why could this be? Backend plugins dump: https://dump.viaversion.com/470446aa9f419965c7afedd21215e4afd0e969d47550950ac5edeb29a0cd7dfd

[Barvalg]