FAIL - install F-droid fails on Moto X4

[mikefuludroid]

Hi there, today I did try to download and install f-droid as I needed some caldav/webdav/carddav connectors.

hence it worked fine on one phone with android,
it failed on my motorola moto-x4 xt1900-7

I am using Android 9, ppws29.69-26-4 patchlevel from 01-01-2019.
External sources is allowed.

After download I open the apk file
Installer starts
asking if I want to install f-droid
I click on INSTALL

… and get an error/msg ‘not istalled’

… if I try on my 2nd phone, vernee-thor phone with Android 7.0 (pacthday 6th dez 2016) it works, too.

Any help?
Thanks in advance!
Mike

[Licaon_Kter]

What application opens the APK exactly? Browser? File manager?

Since Android 8, that application needs to ask for permission to install APKs.