Minecraft Version

1.21.8

Mod Loader

Fabric

Describe the Issue

Whenever I've tried to connect to my friend's server, I get an error saying: "Internal Exception: io.netty.handler.codec.DecoderException: Failed to decode packet 'clientbound/minecraft:custom_payload' " and I discovered that it had been balm causing the issue. So far the only versions I've seen the problem on are 1.21.8 and 1.21.7

Logs

disconnect-2025-09-25_06.51.24-client.txt

This is caused by the client having a newer version of Balm installed than your server.