I have this MC server thats heavily modded and Ive been getting kicked from my server with this being the reason

Internal Exception: io.netty.handler.codec.DecoderException: java.util.zip.DataFormatException: uncompressed size is inaccurate

I and 1 other guy get this and it only happens when doing stuff in my inventory and it happens randomly sometimes it doesnt do it but it usually happens every time i play

Here's what's causing it:

The server is trying to compress packet data and failing when you mess with your inventory. Usually happens with modded items that have a lot of data attached.

Quick fix:

Add this line to server.properties:

network-compression-threshold=-1

That turns off compression. Should fix it.

If it still happens:

• Make sure everyone has the exact same mod versions

• Give your client and server more RAM (like 4-6GB each)

• Update your mods/Forge

The inventory thing makes sense - modded items with tons of NBT data can mess up the compression. Turning it off doesn't really hurt performance on most servers.