A friend of mine noticed, and then I verified, that with Rosegarden
15.12, I can no longer import an audio file into a track. This is
something I have often done successfully in the past.
With the track selected, I selected the "Manage Audio Files" menu entry,
and in the window that appeared, tried to "Add Audio File (a WAV file
(16-bit WAV audio, 14400)). I got an error dialog (attached) indicating
it couldn't import it because the sound file was bad.
So I tried importing audio files I successfully imported months ago -
again there were errors.
I even tried importing audio files recorded by Rosegarden and
Version 15.12 is the version that comes with Ubuntu 16.04 LTS.
If this problem has already been fixed, let me know, since I could
probably get a newer version from the Debian Unstable Repository.