When using the /effect command to give a potion effect to a player from the server window, it throws "[16:29:35 INFO]: An unexpected error occurred trying to execute that command".

The effect is however applied to the player.

When I try to apply the effect directly ingame (example : /effect give @p minecraft:absorption), the game crashes with the following error :

Internal Exception: io.netty.handler.codec.DecoderException: com.google.gson.JsonParseException: don't know how to turn a {} into a component

When I come back to the server, the effect has been applied.

I don't get this error if I create a creative world and try to give myself an effect