Can you please help fix the error: https://pastebin.com/eN8T7rXg

This is using the latest build. v2.1.1

Ref: https://github.com/pixar02/McCombatLevel-Expansion

FeatherBoard API
https://www.spigotmc.org/wiki/featherboard-api/

I am confused, as according to your last note in regards to this. It was revert back to 2.0.1 method so this breaks it now?

The other plugin just have to be updated. That's it.