Hi @quirkius, welcome to the Sonos Community!
I’m sorry to hear that you’re having issues playing from YouTube Music. A colleague of mine raised this with the team yesterday as another user had the same issue (with the same message as well).
An outage for YouTube Music was raised yesterday on our status incident page, but has since been resolved. If you are you still having issues with playing YouTube Music, then it’s recommended to reboot your router, speakers, and controller running the Sonos app.
I hope this information helps!
Thanks for that. This may not have been related to the YT Music incident. My Google Nest devices were able to play music from there with no problem.
I managed to resolve it by logging out of the Sonos app, then logging back in. I was the able to re-add the service in Sonos and all was fine post that.