Network Protocol Error kick when locator_bar gamerule set to true

[justEli]

Expected behavior

Players do not get kicked every few minutes

Observed/Actual behavior

Players randomly get kicked with "Network Protocol Error" when locator_bar gamerule is set to true in Paper 1.21.11. This occurs only when either 15+ players are online or MSPT is 30+. Setting locator_bar gamerule to false fixes the issue completely.

Steps/models to reproduce

Run a server with:

• 15+ players and/or MSPT with 30+,
• have gamerule locator_bar set to true

And see players randomly get kicked every few minutes.

Plugin and Datapack List

CoreProtect, dynmap

disconnect-2025-12-27_21.27.08-client.txt

Paper version

1.21.11

Other

Setting locator_bar gamerule to false fixes the issue completely.

[Doc94]

i cannot reproduce this in local or a server with many players.
Con you provide more info and the full version output?

[justEli]

[15:56:11 INFO]: This server is running Paper version 1.21.11-54-main@6da8af7 (2025-12-23T19:13:29Z) (Implementing API version 1.21.11-R0.1-SNAPSHOT)

There's not much more I can provide than that I'm afraid.

[mbax]

The error reveals the server is behind a Velocity proxy, which is also not mentioned in the issue.

Please share the output of /plugins on Paper and the full velocity plugin list too.