This is possibly caused by not adding an if statement to a nullable object, please fix this I and my friend can't play on my SMP, sorry for little to no context but I really don't know what to do. And it is not generating an error in the console, so there's not much context.

I don't know what that is.

It works when I use it locally but I'm using Aternos which may also be the problem.

they havent added support for 4.1.X yet.

close as outdated. they could had a corrupt jar.

Please update your via* and see if your issues persist - otherwise please make a new comment.