Error message “App not installed”

My App working fine when using AI Companion. I Build APK with Android App without problem.
Download APK file using QR Code.
When install App I receive
Error message “App not installed”.

How to check error reason?

A common reason - the App was already installed before. If that's the case, delete it from your device. Delete the existing APK too. You should be able to find it via 'Files/Downloads' or similar.

Your Topic should be in the Help Forum. This Forum is about App Inventor itself.


Thanks for your support.
Now all is OK.