The error :

https://pastebin.com/hCyf3YeW

Anyone can help me ?

I'm using Magma 1.12.2 :/

Sadly it’s on Bukkit’s side. From what it looks like, you’re using Bukkit for 1.12 while my mod requires 1.12.2. Try updating Bukkit, maybe it will help.

Well, whatever you're using, I don't know. The point is that it's not my fault, and you should report it to the developer of this server mod.