Since a couple of days I have the same problem. Tried everything: uninstall + reinstall Spotify app and Sonos App, multiple resets of my speakers, changed & tried several settings, removed Sonos (in Spotify) as an approved app. and added Sportify again, reauthorize Spotify in Sonos, checked and reset my wifi multiple times, nothing worked!?
I don't know if there is a new issue or if my recent change to Spotify Family has anything to do with it?
Re: Can't connect to Sonos players in Spotify Connect
This is not a solution. I have reinstalled spotify, reinstalled sonos, reauthorised spotify. Still the same problem. Sonos is visible in Spotify's "Devices Available", but it no longer switches to sonos from spotify. Very disappointing, as this was a key feature of Sonos.
Okay, seems to be fixed! I've received a message from Sonos support (see below) saying that they've been loking at this issue for a couple of days - on their advice I removed and reinstalled the Sonos controller app, rebooted my device (just in case), and its working...
Response Via Email (Liam Lewis)
12/04/2017 03:40 AM
Thank you for your email.
I am sorry to hear you have experience issues with Spotify Connect.
Has this issue since resolved itself for you? We have looked into this issue over the past few days.
Can you try uninstalling and reinstalling the app if you still have trouble?
Please reply with a diagnostic number if your issues persist.
Ah well, I spoke too soon... I've successfully cast music from the Spotify app to one of my Sonos speakers, but I then tried to link to a further three grouped speakers and it doesn't respond, it's now 'glued' to my first choice... I'll get back to Sonos. BTW, has anyone noticed that altering the volume in the Spotify app produces an odd popping sound whilst music is paused?
I just "disabled" (because I am not allowed to actually uninstall) the Spotify App on my device. I had done this many times, and tried to enable and open without updating many times, but it never let me, so I was stuck with the newest version that had the aforementioned issue. Thanks to McBernie for posting the link. I installed that version and said NO to updating, and now everything works again.