Custom Recipe disconnects from Multiplayer?

I've got a custom recipe in a Datapack I made, but when I put it into a crafting grid it disconnects me or anyone else from the server. The recipe works fine in singleplayer mode though. Here's the error code: "Client disconnected with reason: Internal Exception: io.netty.handler.codec.EncoderException: Failed to encode packet 'clientbound/minecraft:container_set_slot'"