Concerning APK, It opened to the main page then closed by it self

[Taifun]

@TIMAI2

There could be one of many reasons why your app crashes on start up.

See also

General Tips and Tricks for App Inventor

This list was made by @Taifun Use different screens wisely Before starting to create another screen, first you should think about is it really necessary? See also Building apps with many screens and SteveJG's post about advantages/disadvantages, because in only one screen you also can use vertical arrangements to simulate different screens, just set the arrangements to visible = true/false as needed... If you decided to use different screens, then you should switch them correctly, else you …

Taifun