[CROSS_Hunter]

Well you can follow a few steps because that constant is actually something defined in a_objects include, so that means you have an outdated server version , try re downloading the samp server package and make sure you use pawn from there

Let me know if it works for you or not.

EDIT: Don't forget to add your updated includes into the new pawn and set it as default for opening .pwn files so it doesn't refer back to the old pawn with outdated includes.