Ok, I have made a new project named LearningGame, Made a C++ class called KatGameMode, refreshed project, then opened it. then closed UnrealEditor and built the project in IDE, started Unreal, made the blueprint. BP_KatGameMode. Saved it, then exited and started again. As soon as I try to load BP_KatGameMode I get the error again - Blueprint could not be loaded because it derives from an invalid class. Check to make sure the parent class for this blueprint hasn’t been removed! Do you want to continue (it can crash the editor)?