io.netty.handler.codec.EncoderException: String too big

What the log looks like

io\.netty\.handler\.codec\.EncoderException: String too big \(was \d+ characters, max \d+\)

How to fix it

1. Check the stack trace lines directly beneath `EncoderException` in your log to see which packet failed (such as `ClientboundPlayerChatPacket`, `ClientboundSoundPacket`, or recipe sync).
2. If players get kicked while joining a modded server, install **Packet Fixer** (or **XL Packets**) on both the server and client to safely raise the 32,767-character string limit.
3. Update mods that generate massive tag-based recipes (for example, update TechReborn past 5.3.4 if `Recipe output string is too big` appears in the console).
4. If the error occurs when activating a command block with `/say` (max 256 characters), replace the command with `/tellraw @a {"text":"..."}` to bypass the plain-chat string limit.
5. If a specific block or item triggers a 32,767+ character error on a creative or public server, remove the corrupted block/player inventory data and install an anti-exploit NBT filter plugin.

Check your own log