In the last week my Sonos One stereo pair running Google Assistant has started giving me this message frequently when I request to play, pause, resume or stop something. Sometimes it’s stuck on this error - I can ask it repeatedly and keep getting the same response. That’s very annoying when it’s playing a stream and I’m telling it to STOP!!!
Google Assistant itself is not affected as far as commands not involving Sonos streaming - it only affects media streams starting or stopping.
The Sonos app is unaffected. Even when GA is refusing to start or stop a music stream repeatedly because “Sonos is not available”, the Sonos app has no problem doing it, and correctly shows the streaming status of the speaker.
I can also ask my nearby Echo Dot to play or stop music on Sonos, and it works fine.
So which side is at fault here, Google or Sonos?
At one point I tried unplugging and replugging the primary Sonos One speaker of the pair. When it came back up, it would only flash red when I said a “Hey Google” command. Checking the Sonos app, my GA voice assistant had disappeared. I had to set it up again from scratch. After which it worked fine for a while before it began telling me again that Sonos is unavailable.