Every now and there is the error message
“The selected output device is not available
Please connect HifiBerry DAC Plus to the unit or select a different output device from playback options”
as reported here: https://forum.volumio.org/please-access-version-587-2019-t12696.html#p65261
Sound is working nonetheless. My DAC is an original Hifiberry DAC Plus on a Raspberry Pi 3B. Volumio version is 2.599 (fresh install). The error message seems to appear after booting, but as it happens unpredictably I have not been able to capture a log so far.
Issue reported on GitHub: https://github.com/volumio/Volumio2/issues/1788