Error installing apk from non-default repository

What did you do? (clear steps if possible)

I have set up an F-Droid server instance on my personal server (which mirrors an apk from the Brave Android Github repository) and added my repository in the F-Droid client. The apk successfully downloads when I click the install updates button in F-Droid.

What did you expect to see?

I expect to see the app automatically update or at least let me manually update it.

What did you see instead?

The app fails to update automatically and instead there is an F-Droid notification telling me an update to the app is ready. When I try to manually update it, after asking about any new permissions, a new screen appears (I'm guessing the Android installer) with the message

Parse Error

There was a problem parsing the package.

When I click OK, it returns to the F-Droid Client screen with the message

Error installing Brave

Failed to install due to an unknown error.

This message appears twice, one hidden under the other.

Other

Using a root explorer, I tried to install the apk directly from the F-Droid cache (/data/data/org.fdroid.fdroid/cache/apks/repo_name--1) but I am presented with the same

Parse Error

There was a problem parsing the package.

I can copy the apk from the cache into a non-root folder & successfully install it from there. Changing permissions on the apk in the cache folder (e.g. to 777) does not seem to help. Apks in the default repo cache folder and at least one other 3rd-party repo also will not install from the cache but do install properly through the F-Droid client.

I wasn't sure if this should be filed here or under the F-Droid Server.

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