Changes in DownloadManager Behavior

From what I can tell,
relatively few apps use DownloadManager for
downloading files from Web URLs. If your app happens to be one of them,
note that some DownloadManager behavior has changed, in Android 5.0
and again in Android 6.0.

Specifically, starting with Android 5.0, the app behind DownloadManager
appears to be monitoring app uninstalls. If your app uses DownloadManager,
and the user later uninstalls your app, exactly what happens depends
on the version of Android:

Android 4.4 and below are oblivious to the uninstall, so everything
remains as it was prior to the uninstall.

Android 5.0 and 5.1 note the removal of your app and remove your
app���s downloads from the list shown in the Downloads app. However,
the files that were downloaded are still there for the user.

Android 6.0 not only removes your entries from the Downloads app,
but also removes the downloaded files. This is true even if you
specifically downloaded to a location that should survive an uninstall,
such as via setDestinationInExternalPublicDir().

Presumably, this is to help clean up cruft left behind by since-removed
apps. However, the user may not realize that removing your app will
also remove files that they obtained via your app.

Your primary options would seem to be:

Stop using DownloadManager

Use DownloadManager, but then move the file away from the downloaded
location, to some other place where the user can continue using the
file even after uninstalling your app

Use DownloadManager, but educate the user about needing to move
the file themselves by one means or another, should they elect to
uninstall your app