Programmatically install an apk in Android 7 / api24

Question

I am trying to get my app to automatically install an apk. This works fine for api<24. But for 24, it is failing. Android has implemented extra security:

Answer 1

In my case on android 8.0 problem was in

More detailed how to get this permission Exception 'open failed: EACCES (Permission denied)' on Android