Cannot update from version 6.000

I originally installed K-9 from F-Droid on an earlier phone (OnePlus 6) and migrated it to my OnePlus 8T early last year. I was able to update it as recently as three months ago (Oct 2022), but now I get an error when I try to get the newest version.

F-Droid shows 6.310 as the latest, but it appears that 6.400 really is the latest. When I attempt to update to the latest versions shown at the bottom of the F-Droid view, it simply pops up “Not installed”.

I saw that K-9 was available in the Google Play store, but it refuses to offer any opportunity to upgrade the app.

Any ideas what I need to do to either make F-Droid work, make Google Play let me update to the latest version, or otherwise install the latest version (while muttering rude statements about their ancestry)?


Google Play version will have a different signature than the F-Droid version. You won’t be able to install from one and update from the other. To switch between them would require the application be removed prior to installation from another source.

Have you by any chance activated Google Advanced Protection for you Google account?

When GAP is active, you cannot install new apps from other sources than Google Play. So no side loading and no F-Droid.

You are only able to update already installed apps from other sources, that were installed before GAP was activated.

Since you migrated phones, The APK may have been migrated and installed by OnePlus before GAP was synchronised to you new phone. This would leave you with an “installed” app, that is not installed according to GAP. Thus F-Droid update would fail.

Also, there seemed to be a bug with OnePlus and GAP signatures. However, that was fixed a few month back… Have you updated to the latest version of OxygenOS?

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“Have you by any chance activated Google Advanced Protection for you Google account?”
I hadn’t even heard of it until your message. I am pretty sure I don’t have it activated anywhere.

So, from your response and linkp’s, it look like I need to export from my current installation, delete it, install the latest via Google Play, and then import.

Thanks for the answers, both.