Runtime error: Unable to add window - token ... is not valid, is your activity running?

[Boban (Boban Stojmenovic)]

How to switch screens correctly

I see many issues done by users because they switched screens not correct. This below is now just one of many other solutions: [blocks] If you dont open/close screens correct your app will get possible runtime errors. Possible errors: (example) Unable to add window -- token android.os.BinderProxy@45d459c0 is not valid; is your activity running? Iam sure you don’t want that. Then please do it in the future and switch screens correct. General Tips and Tricks for App Inventor/Makeroid …