If you're getting this error message, it usually means Rocket League has had an update, and Bakkesmod currently isn't compatible with it. In this instance, it's a waiting game. It can also mean your Rocket League needs an update as the error message doesn't distinguish which program is outdated. You can sometimes force an update by navigating to the menu pictured above, but you will probably only need to do this if Rocket League has recently updated. Finally, if none of the above works, completely deleting Bakkesmod and giving it a clean install has been reported to fix problems by several users.