Good night @NathanWolf
I was testing the plugin using the RPG configuration, I don't know if I need to do something else, it is necessary to install another plugin or what happens, when I try to use the "/cast attributeselector" command the icons do not appear and when I click on one of the options menu (GUI) nothing happens, I check if my attributes were changed with "/mage attribute" but they remain the same.
Also when executing the command I get this in the console

and when using / cast class selector, I get this error

I am using minecraft 1.12.2, the plugin version is 7.3.7

wow xd it was because of that, thanks a lot bro

Your plugin version is outdated, I think this is the problem

Hi @PhvntxmX , could it be that, there will be no problems if I download the version for 1.16 even though I am using version 1.12.2? sorry I'm too noob in this of the mc servers

I think it will work, since the latest version of the plugin supports 1.9.3 and further.

😮 ok thank you very much, I'll try it ^^