It means you've run a program that uses a newer version of nw.js. It's harmless. You can go into your user profile folder and delete some things to get the warning to go away, but it'll come back as you run different RPG Maker MV/MZ games or other nw.js programs.
Steps:
Press Win-R or right-click on the Start menu icon and pick Run.
Put "%LocalAppData%" into the box and press Enter.
Delete the "nwjs" folder.
Open the "User Data" folder, then the "Default" folder.
Delete the files "Web Data" and "Web Data-journal".
Thanks did that and the error message went away. As long as its harmless