I had this issue a few times and it was due to a corrupted blueprint in my case MyCharacter, you can try and replace your blueprints from within the project saves folder ue4 auto saves your blueprints every so often. If you don’t think it’s due to a corrupted blueprint, it could be a null pointer issue within c++, it’s a good idea before trying to access members or functions from an object to first if(object) to insure your pointer is actually pointing to the correct address in memory as the object is stored.