Unable to install .apk packages on FP3

Dear all,

since November 2021 I have been unable to manually install software from .apk packages on my FP3. Prior to that it had worked pretty well.

I am running a FP3 without a google account. With a few exceptions, among which are the official Corona Warn App from German Robert-Koch-Institut or the alternative camera app “simple camera”, I solely use the pre-installed apps, .

Until last November I had extracted the package using APK analyzer on another FP3 and then sent the .apk file to the FP3 without the Google Account. At the beginning of the installation process I could grant the permission.

Unfortunately, this procedure is no longer working. When tapping an .apk file, e.g. an update to an existing app, I am still prompted to grant the permission to install - once or permanent - but when I click it nothing happens. No setup/installation is being carried out.

My first thought was that the package was corrupted but the phone won’t let me install any other .apk file, too.

Is this a known issue? Is it down to the latest security patch?
I’ve browsed through all the settings in my phone but can’t find anything helpful.

Thanks for any reply


From memory: You can enable ‘developer options’ and then you can :slight_smile:

There’s often a warning about alliwing such

  • FP3 and FP4: Settings > About Phone > tap build number 10 times
    Settings > System > (Advanced) > Developer Options > ON

I wonder why you went with this difficult route, given both those apps are available (in slightly modified form in CWA’s case) on F-Droid. And the F-Droid website also lets you download .apk files directly if you don’t want to use the F-Droid app (CWA, Simple Camera). Seems much easier.

No clue why you’re having this problem though, I wish I could help instead of just suggesting a workaround.


I download various, apk(s) mostly from apkpure, and no problem ?

Problem fixed …

Sophos Intercept X security software was the culprit. Sophos scans apps at some point during the installation process. All that used to happen in the background eventually showing a notification of the scan result.

I guess Sophos was updated recently as now, after tapping the .apk-file, I’ve got to choose Sophos instead of package installer. Sophos then scans the .apk and shows a button that opens an option to install a package from an unknown source, just like before. So it’s just an intermediate step.

Thanks for your extremely quick replies anyway!


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