How to Fix Android App Not Installed Error?

Question

I have developed the app by Android Studio, and build it to signed apk with V1 and V2.
It could install in my phone successfully.
But, when I uninstall the app,

Answer 1

I searched entire SO for the solution to this issue. Even disabling Google Play Protect didnt work. Creating APK with debuggable=false didnt work. I stumbled upon some answers which pointed me to a blog(link at the bottom)

What worked with me was

Goto Android Studio -> Build -> Build Bundle(s) / APK(s) -> Build APK(s)

However, I still dont seem to understand why a signed debug APK wont install on my device.

Couple more things to remember.

1. You will see App Not Installed error even if you have old APK installed on the device and you are using Build APK(s) APK to install to update it. The package installer of Android is no more showing user friendly messages.
2. If this method does not work, uninstall all variants of this APK from device and then try again.

More Info: https://commonsware.com/blog/2017/10/31/android-studio-3p0-flag-test-only.html