Could not serialize

[albsein9]

I am making a mod that has a command that requires me to create a new ArgumentType called FormationArgument. Everything works fine on a singleplayer world, but on a modded forge server something changes. Whenever a player logs in, it says 

[Server] Netty Epoll Server IO #1/ERROR Could not serialize com.albsein9.customstuff.commands.arguments.FormationArgument@326eceb4 (class com.albsein9.customstuff.commands.arguments.FormationArgument) - will not be sent to client!

 

Now I usually discard these warnings but I noticed that typing the argument for my custom command was showing that it was incorrect even though it was correct, as it works when pressing enter.

It looks like this when still in the ChatGUI

 

 

Note that the command does not have this behaviour on a singleplayer world. On a singleplayer world, when you finish typing the world 'circle', it becomes green.

 

So I was wondering if these 2 things are correlated, and if there is a way to fix this for my server.

Also, here is my code

https://paste.ee/p/UOKZH 

[aritod]

7 hours ago, diesieben07 said:

You have to register your argument type using ArgumentTypes.register.

^

Edited May 25, 2021 by aritod