KnownPacksFix

This plugin fixes a Velocity proxy issue that can cause clients to disconnect during the Minecraft 1.21+ configuration phase when too many “known packs” are sent. This often results in errors such as KnownPacksPacket or corrupted frame exceptions, especially in heavily modded environments.

The issue occurs during the handshake/configuration phase when modded clients and servers exchange a large number of mod or configuration packs through a Velocity proxy, exceeding practical protocol limits and leading to unstable connections.

This plugin applies a compatibility workaround to reduce or prevent these disconnects, improving stability when joining modded servers through Velocity.

Fixes “too many known packs” / KnownPacksPacket disconnects
Improves Velocity proxy compatibility during the configuration phase
Designed for modded Minecraft environments (NeoForge-focused, may work with others)
Helps stabilize connections on heavily modded servers

Why this exists

This was created while running into the issue personally on a modded 1.21+ setup behind Velocity. There wasn’t a clear or reliable fix available at the time, so this workaround was developed and shared publicly in case others encounter the same problem. If it helps your server, feel free to use it — you're welcome. :D